>>317837I bought this for 50$
fits enough to survive plus some.
I put my first aid kit in the front pocket because it has a velcro backing and fits perfectly in there. I could easily attach it to the front, but why bother?
I think if you're really looking into older military packs get a Gen I or II ILBE. They're relatively cheap and can withstand the elements. But be careful because they are a bit heavy.
Learn what you would actually need to bring with you, and get a pack based on that.