The number selection could loop backwards (on the Xbox hit the left pad direction) to go from 1 item to whatever the maximum is.
Also, you may want to take 2 or 6 items out of the battle tower chest, but you're probably never going to need exactly 37 of anything. The number selection could progress as 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50 (or increment by one when the button is pressed, or 5/10 if held down). On the Xbox the right and left pad directions go up or down by 1; the up and down pad directions do nothing, but could increment by 10 (on the PC you could use a Shift/Ctrl key plus whatever the normal key is to increase the increment).
Since a variable increment is fairly common with zoom levels, scroll speeds, etc in many programs, I assumed the lack of such features selling/moving stuff meant Larian didn't figure people would be doing a lot of selling (so it wasn't a high priority), or they wanted to discourage doing so.
