When buying a brand new backpack, I’d say that anywhere between $20-$30 is a reasonable budget. Anything more than that would be considered extremely expensive to me. You have to remember that if you’re taking a bag to school or work every day, it will probably get a little dirty on the commute or during the day. So you don’t want to spend a load of money on a bag for it to get trashed. But, the more you spend, the higher quality it’ll probably be. But it all comes down to what you will use the bag for in terms of budget.