I’m a big fan of Trader Joe’s generics. You have to know which style of brew you like; I like lagers and am a big fan of their Bock.
Buying in bulk helps. The Ralphs in 4S typically has a deal where if you buy Four Six Packs at once (can be different types) the price comes down a lot. I’m talking $11/6 pack down to $8 per. Costco is similar pricing but selection choices can be limited.
As for a macro brew, Sam Adams isn’t bad, and Blue Moon is okay.