Given that sleeping bags are for all intents and purpouses fairly similar in construction and the only real difference is the down loft power, What sort of prices do you think is reasonable for the different grades of down ?
I have seen 600fp sleeping bags at 400 dollars, which seems a bit steep.
Loc: Portland, OR
Speaking very generally, if two otherwise identical sleeping bags achieve the same loft, then the only difference between ones using 600 fill power down and 800 fill power down will be their weight. And the less loft that is required, the less this matters.
As for cost, I wouldn't concentrate too hard on fill power as a significant factor in how a retail price is determined. The labor and all the other materials are going to be a large chunk of the manufacturing cost, to which you must add transport costs, marketing costs, and profits.
In the end, temperature rating, workmanship, durability, cost and total weight are all going to matter. The fill power is only one fairly minor factor to consider, even though it has become increasingly visible in marketing terms.
I'm not sure what a satisfactory answer to this question would like like. I probably wouldn't pay $400 for 600fp sleeping bag... though there are circumstances where it might be a good deal I guess.... a -20°F bag? I am always looking for a good deal. The last two bags I have bought have been quilts from enlightened equipment. They seem like a great deal to me. Before I bought the EE quilt I was strongly considering a western mountaineering bag and a feathered friends bag. Both are more expensive but seem like a good deal for something you can buy in a shop (with the requisite overhead and middlemen costs).
The EE website certainly eliminates every single other variable for making a price and weight comparison. I suspect that the sales price difference closely tracks their cost difference, but it would be easy to check against bulk down prices since the EE selection tool gives you precise weights of down for every combination of temperature rating and fill power. That seems like a good place to get calibrated on market price. If you see comparisons on other seemingly-similar products that are way out of line from that it's probably either a great deal, a ripoff, or a subtle but possibly-important/expensive feature difference.
I disagree that other than fill power and cost all bags are alike. Here are some other major things to consider.
1. Baffle system. Down has to be contained and there are several baffle systems. The good ones overlap so there are no sewn threw cold spots. If the internal baffles (that you cannot see) are too flimsy, they will break with use and washing and the down will no longer be evenly distributed. 2. Zipper and zipper baffle. Smooth snag-free zipper operation is essential, as is an adequately large baffle. Lots of cold air can seep through zippers so you need a baffle to keep that area covered. 3. Hood fit and design. A good hood should fit well and cinch up comfortably in your preferred sleep position. A good collar baffle is essential for colder temperatures. 4. Material specifics. Very light weight bags may have some problems with down leakage if their lightness is due to a more open weave. There has to be a balance between breathability and weave tightness. You do not want a material that is so thin that you will tear it with years of use or leak down but it cannot be so tight that it does not breath. 5. Quality of workmanship and materials. The best materials will not overcome shoddy sewing. The best sewing cannot overcome poor materials. Not all nylons are equal! 6. Types of down- goose of duck, treated waterproofing or not, exactly what is used for the waterproofing. 7. Overall bag shape- basically mummy or square with many smaller variations between. 8. Fit. If the bag is too big for you or too small it will not be a good bag for you. They now make women's versions as well that offer more warmth (fill) for the same temperature rating and are shaped slightly different.
Do not discount synthetic bags. They have their place and although a bit bulkier and a bit heavier for a given temperature rating, they are considerably cheaper. Probably better to buy a quality synthetic than a shoddy down bag.
PS my current bag was originally $600, over 15 years ago, and would cost over $800 now to replace. It is worth every penny. I go cheap on some of my gear, but NOT my sleeping bag.
Well the theory was that most sub 4lb bags have one baffel system, that the baffels trapezoidal box etc are similar. They mostly have zipper baffles and hoods.
The actual fabrics are important, but most are expensive some are quite expensive indeed, but not to the point of serious money.
The mountain equipment bags are probably sewn in the same place as the vaude bags etc ie a factory in china.
Even the price discrepancy between the same manufacturers model at a different temerature ratings gives you an idea of the expense of down, and all they have to do is take a bigger handfull and ram it in there. I should not think the difference in model ratings is due to the addition of an extra baffel layer in most cases unless you select an arctic 8lb down bag.
Its just that there seems to be alot of cheaper bags, then the starting range of about 500fp down by well known manufacturers. The 850fp goose down seems to be about the best you can get generally, duck down being less fp.
Two high end sleeping bag companies sew bags in the USA- Feathered Friends in Seattle and Western Mountaineering in Marin County Ca.
There are cheap "knock off" versions of proprietary materials. Not every factory in China or Vietnam, or wherever, produces the same quality. The baffle systems you cite are NOT equal in warmth. The down itself can vary in quality.
Another advantage of the two high end companies I cited above is that they really stand behind their products. I have owned bags made from each for decades.
It all depends on your needs and budget. If you backpack a few times a year and in relatively mild climates, then a cheaper bag may be just what you need. On the other hand, if you are out 50-100 days a year and backpack in more extreme conditions, then a more expensive bag may be justified. I doubt many if any PCT or CDT thru-hikers use off-brand bags. Definitely, if you are looking for maximum warmth for minimum weight than you are going to pay a lot. Each of us had to decide how much that extra cost for an ounce saved is worth.
I am not saying there are not some pretty good cheaper bags out there. As for the expensive bags, you have to separate the sales pitch from the actual quality. High dollar is not a guarantee of the best bag; but the best bags are more expensive.
I must say that even though there appears at first sight that the baffle construction is better in diagonal construction, it is not enough to compensate for the weight penalty. Using box walls and a bit more down seems to come out lighter.
This also is an example of the cost of good down,this being a prohibitivley rare class, as everyone could probably not be furnished with this type, theres just not enough to go round. The price difference in the different teperature ranges of this model is extrodinary.
I think, the fill power primarily influences the weight of the bag.
The thing I would look for first is the temperature rating. Although the manikin may be different from your body composture, he's always the same one testing the different bags from different manufacturers.
While some guy from the company may be able to sleep at -10 with only undies on, another guy might be freezing his butt off at 0 wearing a merino first layer and a hat. (i.e. the "company temperature rating" doesn't help you compare different brands)
Find the temperature rating you need for yourself (e.g. 0 degrees Celsius) and start comparing different products based on that.
You will realise that an 800 cuin goose down bag can deliver the same temperature rating as a 600 cuin duck down bag at maybe 2/3 to 3/4 the weight. The reason for that is simply that the 800 cuin down takes up much more space per weight than the 600 cuin down.
Also, the fill power of the down is affected by the material and box construction of the bag.. The down needs to be able to loft fully or all that "fill power" gets wasted.