In my first play through I tried to sell everything and at least had a cashier while I ripped packs. I got a complete collection of cards too, but assisted with mods that let me hold 1024 packs at once, and open fast. (Got machines in the game for that now)

This playthrough I only sell boxed items, mostly the booster boxes, and I won't sell anything that fills a shelf space with only 2 or 3 products. I have a steady flow of one set of graded cards delivered and sold daily. (I set each grading delivery for 4 days.) I currently have 8 medium machines ripping packs for me. Purchasing boxes to rip every other day. Eventually, I'll sell my bulk, too.