Campmour is the only source I know for new external frame backpacks. Unfortunately, the ones they have are either for youth or they are too heavy.

World Famous external frame backpacks were popular back in the 80's. They are about a pound lighter than the Jansport and other brands. There are three types. The Everest, Northface and Mont Blanc. Essentially, they are all the same pack except for the belt. Be sure to get one with the big waistbelt.

You can usually find them on Ebay or Craigslist.

If you do buy new, be real careful to look at the torso size. Some of them are too short. Also be real careful to look at the weight. Around 4 1/2 pounds is reasonable for an external frame pack.

In my opinion, the pack should be selected first, but not purchased. In the case of used, buying first is not so bad because you can always sell it for about the same price.

Then select the gear to fill the pack. The reason I say this is the size of the pack will drive a couple of your purchase decisions. Mostly the tent and the sleeping bag. The smaller your pack, the more you will need to spend on these so they fit.

This advice goes against conventional wisdom of buying the pack last so the gear fits.

The most important item in your pack is the sleeping bag. If you can afford it, spend a lot here. If you have to go cheap, the Alpine 20 from Sports Authority will work down to the high 20's. Going cheap forces you to have a bigger pack.

To get a tent that doesn't leak you will have to spend some money too. Walmart tents are great, until it rains.

In my opinion, the cheapest and most efficient way to buy the first round of gear is to make a list of gear you want from REI or someplace. Decide what things you have that you can use - like clothes. Then make a plan to purchase your first dream pack overtime rather than all at once.