So I'm planning to build two racks for 32qt sterilite tubs. But can't decide on the best and most economical configuration.

I would like to build them as high as possible as I don't have a ton of floor space. Originally I was thinking 10 high until I started to figure out how many sheets of xpvc I will need. Building 10 high seems to have a lot of left over scrap. So now I can't figure out what's the best way to go. Two side by side racks, 2 stackable racks, 9 high, 10 high, etc?

Any advice would be much appreciated!