We used these 4 Level Storage Rack with Zinc-Plated Wire Decking - Sam's Club
Because as you kind of planned already, with 2 sets and enough space you get 3 sets of shelves. Can't remember shelf capacity off hand but its a lot. More Solid than anything else that they had out at Sams....very stable and cheap @ 150.00. Out of stock online presently, but I bought them at the local brick and mortar sams...so you may be able to check.