My favorite cheap makeup item is mascara. I spend on skin care and things that I directly apply to my skin, and I think good lipsticks and eyeliners are important. However, when it comes to mascara I can just go with something like Maybelline.
Face powders are always cheap, maybe with the exception of Cover Girl and other brands. I recently saw make-up being sold in a convenience store, and lipstick only costs around $2.23. It's a local brand, so I wonder if it's of good quality considering the price.
I have bought a number of cheap brands of nail polish and I have found that I really love the Sally Hansen nail polish that costs just 2.00 at Wal-Mart. The polish goes on nice and smooth and they have some pretty colors. As someone stated in a previous post, using a base coat and a top coat makes it last as long as a more expensive one.