I suggest that you add a 'pocket' to the back pack, so that when you win stuff after a battle, you can decide to keep it or put in pocket, (which would not change the maximum capacity of the present back pack), and that way when you go to the bazaar you don't have to sort stuff and decide whether to keep or sell stuff. This would expedite the process so we can spend more time on spending gold than shuffling though stuff.
In the Sell area of the bazaar, you would simply click pocket and everything you put in there to sell will be listed and all you have to do is click 'all' and okay the sell process, like it does now, just add a pocket option to that area for selling items in your backpack.