Looking to get my fastass off the couch more this year and do some hiking. I plan on making as much gear as I can but one thing that I just can;t get around is a good backpack.

Money is tight for me so I am looking to get a backpack under $100 that can carry what I need for 2-4 days of hiking. Was just going to get a milsurp alice type bag but seems like there should be a better option. I'll go cheap this season and invest more next year, but I don;t want to blow a bunch of money on a bag/gear and then be short on funds for actually going out.

tl;dr need a back for less than $100US