I tried searching for it, and didn't find anything specific. Forgive me if I missed it.

My question is like the subject says. What should I not buy used? (excluding personal hygiene gear for obvious reasons) And probably another good question is as a newbie what should a buy used as I'll be learning what I like?

I need to buy gear for my wife, and a few items for myself since most of my gear is old and or very heavy, and my lovely wife has nothing. I would not rather break the bank, and I know I don't need every little thing. But as I've been researching important items like tents, packs, sleeping bags, outer clothing and other gear it starts to add up rather quickly.

Thanks for the help!

There are few hard and fast rules. But, if I were looking at a used pack or tent, I'd check all the seams carefully, look for signs of wear, double check that the zippers run smoothly and aren't missing teeth (the sliders are often the first item to wear out on any gear), look carefully at the tent rain fly for signs the waterproofing is peeling off or worn out. You don't want gear failing on you mid-hike. If the gear is intact and fully functional, you're probably ok to buy it.

btw, I would never buy used foot wear, but I expect you'd know that much.

I will buy almost any gear used. The only major exception is down sleeping bags.

If you're near Salt Lake City, the REI there rents most everything you need to go on a backpacking trip. See what they have for rent, and you can get an idea from rentals which direction you want to head when you're ready to buy.

Additionally, check out Section Hiker's site/blog. He's got some great information about various gear for various weather, etc. A lot of information there.

I guess it really depends on what condition an item is in, as mentioned. But I would agree, not so much boots. Sleeping bag is a tough one, but if it's a good one and it's been well cared for it might be worth a shot.
Best option if available, as JW mentioned would be to rent some equipment first.
And you're right, good equipment ain't cheap and it adds up quickly. Good news is, with proper care it'll last a long time.

You'd definitely want to buy from someone you trust to have cared for it properly, but I'd probably be less likely to buy a synthetic bag used, since the insulation breaks down, and they're less expensive anyway.

I would only buy used gear if it was priced right. Do some looking at sales on new gear first. I think most people want too much $$ for used gear. If you are careful you can get good new gear for nearly half off. Nylon deteriorates over time (shoe leather also dries out) so even if never used or worn, a 10-year old item may be worthless. A never used down sleeping bag will have less loft if someone has stored it wrong (stuffed in a tight bag). A tent can look good but still leak. Test it with a hose or sprinkler.

I would not buy a used sleeping bag, unless it is from someone you know and are sure it has not been used much and was really clean. For me it is simply the "yuk" factor. If it smells at all, do not buy it. Never buy it unseen. If it is more than about 5 years old, I would also not buy a used bag. And do not buy used if you do not have proof of what it is made of. You should be able to look up the item based on its label.

A pack should be fitted. OK to buy used as long as you can actually try it out with weight in it before buying. When you buy a new pack you can return it in 30 to 90 days if it does not work while trying it out at home. Be sure you can do the same for a used item.

To me, there are a lot of down sides of buying used because most the time you cannot return it, you have no warenty and you really never know for sure how it has been treated.

There are other sources for budget gear, some of which may be cheaper than some used gear. In fact, try searching your house, first--she may already have some of the items! Here's an example. Here's another. For example, she may already have many of the clothing items (as long as they aren't cotton). If she already has comfortable athletic shoes, they'll work fine. Less than half the clothing I wear for hiking is specifically designed for backpacking. And even some of my stuff that was bought specifically for the outdoors gets worn at home year around. If you have a Costco membership, start there.

Two specific items, pack and shoes, do need to fit well--a good fit is essential for comfort! The pack should be fitted with gear inside (sandbags or other weights just aren't the same), so the pack should be bought after most of the other gear is acquired.

Lots of useful articles here! Includes the next step up from the Frugal $300 Challenge

My experience buying used down sleeping bags online has been very good. I have bought several different older bags online and have seldom had any issues with them after cleaning and fluffing them up. That said, there are several things to watch out for. You aren't going to get a Western Mountaineering bag cheap. You may get an older, decent name bag for a good price, say $30. Very few people will give you accurate weights and measurements, so you take some chances there. I don't think that this is from dishonesty as much as it is just simply not appreciating haw important these are to buyers. I have several bags that are just too small for me to use comfortably as a bag. They can often still be used as a quilt. I have a very nice Trailwise Slimline bag that is much too small for me, but is fine for my wife. I have a Gerry bag that I really like and a couple of heavier bags with great loft that I use for cold weather. As long as the bags are name brands that you can do some research on and you don't mind patching a hole, the risks aren't that bad. The down bags really do hold up much better than synthetic bags over the long term.