Try Walmart or Sam’s Clubs — Olive Oil can be found in quantities to take a bath in.
We get our general-purpose olive oil at Sams pretty cheap, but it’s hard to find the dipping-grade stuff around here. We manage though. Same for good balsamic. That junk on the shelf at Wal-Mart is about it. I swear it’s regular distilled vinegar with artifical color added.
The Internet rules.