Our local department store has quite a display of randoseru - traditional Japanese backpacks. They are given to a child entering their first year of school, and are built to last, with a price tag that reflects the quality and workmanship. The red one on the top row in the middle was about $700 USD. While they aren't all that expensive, a new leather randoseru will probably set you back at least $300 USD.
Generally girls carry red bags and boys carry black, although you will occasionally see some variation - most often pink and blue.