PBR for the price....
I enjoy Labatt Blue quite a lot. If you haven't tried Labatt Blue, it is definitely different than Budweiser and all those kinds of beers, and you can find 12 packs them for just a buck or two more it seems. Killians Irish Red is another cheap beer with a distinct flavor. Michelob can be on sale from time to time as well.
But it goes like...cheap beer (natty ice), cheap normal beer (bud, budlite, etc), more expensive cheap beer (killians, michelob, labatt), then just expensive beer that is never really cheap.....
Favorite beer is heineken or becks though. Summer Shandy is great, and so is Corona also, but those are far from cheap.