Leather school bags
Overstock has a lot of different leather bags on sale as part of its back to school offerings. This three-way bag (over one shoulder, both shoulders, and hand strap), above, is $50 (orig $100). Leather mini-backpacks are $25 (orig $90), a classic laptop/portfolio bag, below, is $80 (orig $170). 
I also like the Alpine 14-inch messenger bag, below, for $25 (orig $60), even though it's not leather.
