Of course it depends on how long you are going to stay out in the backcountry as to what size pack you need but I bought a cabelas ultralight hunter 5000 (i think that is what it was called) in outfitter camo a few years back when it went on sale for less than $200 . If you dont care about the pack being camo, you can get a good deal on just about any internal frame. You can check out backcountry.com, mountaingear.com and steepandcheap.com for some really good deals also.
I would go to an army surplus and snoop around. There is great stuff to be had that is durable, functional, and budget. Craigslist in Denver is loaded with cheap packs,tents, and other camping stuff. If you are on the southern end of WY it would be worth a day trip if you could get the logistics worked out. JAX here in Fort collins, about an hour from Laramie, has an excellent supply of Army surplus and will ship it to you.