Are you talking commercially available or homebrewed? It really depends on what you consider "cheap" too.
Commercially available - whatever micro is on sale at the time, or whatever micro is close to you that can self distribute/fill growlers.
As you are in PA I would assume that Sam Adams is pretty cheap.
As for homebrew - any 2-row based smash recipe is pretty damn cheap to make; aim for 5% abv, use US-05 yeast, 1oz of high AA or 2 oz of low AA hops.
as for inbev/sabmiller crap it's all pretty much brewed to a price point, and in my opinion it all pretty much sucks, but YMMV
There are also mixed drinks for the boat as well, they are cheap to make and you control the potency, margaritas? cheap and potent.