I bought a medium sized High Sierra camping backpack for $90 in the summer of 2008. I lived out of that bag for two months while hiking around Europe.
Then, after I made it back home to the states, I used it to carry my groceries to my apartment by bike or bus for the last seven years, during hundreds of trips. It has held up very well. The only problem with it is a single zipper tassel is threadbare and one pair of clasps is broken. Otherwise this thing is seemingly indestructible and allows me to carry easily 50-60 pounds worth of stuff.
All for a simple, one-time payment of $90 in 2008.
I sincerely doubt I've ever made a better purchase, or put an item to better use and re-use. I'll be very sad the day that backpack finally falls apart.