As far as dirt cheap goes, it's Natty Light since High School. Step up, Coors Light. The following are the cheapish beers that I legitimately enjoy. Very cold. American: Highlife Mexican: Carta Blanca Chinese: Tsing Tao Japanese: Asahi Germany: Spaten Netherlands(?): Amstel Light
I have been having some Old Milwaukee (not to be confused with the barrel of shit that is Milwaukee's Best) and its not bad for what it is..far better than PBR and I think I'd take it over bud. Considering I got 2 24-cases for $4 (there was a rebate...) I would have to say it was the best beer for the price ever.
Not sure how cheap you wanna go, but my favorite cheap is "GourmetBryggeriet"'s double bock, which is around 2,5$ for half a litre. 4 for 2 $ on sale...
Sucks - the two cheap beers I love are impossible to find here - 1> Yeungling 2> Mich Light - ever since ultra came out, finding Mich Light is harder than spotting a chupacabra