How big of parts are we talking here? Home Depot sells "masonry tubs" or something like that. They're big, durable, and CHEAP. I usually use that for larger parts, but if you're thinking about something like a body panel I can't help you with that.
The bins I use are $6 for the one thats 28"x20" and $13 for 2'x3'. They're both about 8" deep, so you can fit most anything in there. I soaked my lower control arms in there to get the gunk off of them before I did anything else.
Links below:
Small
https://www.homedepot.com/p/Plasgad-...102C/205451585
Big
https://www.homedepot.com/p/Plasgad-...101C/205451550