If you want to shoot black and white, go to Freestyle Photo
and buy the Arista Premium film; that's a Freestyle store brand that is made by Kodak. The 100 version is really Plus-X, the 400 is really Tri-X. $2 a roll, 1/3 what these films sell for at my local camera store under the Kodak names.
For color, go to Walmart and check out the 4-packs of 24 exp. Kodak and Fuji color film. Fuji 400 is $8 for 4 rolls. Very cheap! The kodak stuff is a little higher priced but still cheap, and they have 100, 200, and 800 speed as well from both manufacturers.