If $50 is your limit, there are two options: surplus and a good heavy sewing machine. Surplus is a minefield. I never buy anything unles it's listed new or excellent and stated as true issue( not "type", which is cantonese for mainland China junk).Even then you will want to inspect for worn or repaired straps etc. Access to a good shoe repair, saddlemaker or boating shop will enable you to sew heavy canvas or leather replacements or custom items. Surplus tends to be heavier. My rucksack features a steel frame and canvas worthy of a clipper ship. The dull colors are both boon and bane.Sometimes I want to be subdued while watching wildlife. Then I lay it down and it blends into the terrain. Strips of reflective or bright tape solved that. You also risk the smell of storage. A can of fabric spray cleaner, smudging with sage smoke and a good coating of scotch guard made mine socially acceptable.