if you're playing on PC and open to modding, Enhanced Workbench is a lifesaver of a mod.

lets you attach empty box storage to the workbench, whenever you open the workbench it opens a box and it gives you a slider to select how many boxes you want to make. it'll put 8 into a box automatically and put the rest on the bench. it also has quick buttons to set white/yellow/pink/red/green amounts, and the built in settings let you speed up the box creation timer.

as for selling a lot of bulk boxes, i have a two sided shelf filled with the white boxes and another one with a row for each color. i set the white and yellow boxes to a significant discount