[Posibyte]

I always recommend the DE0-Nano. It's getting a little old, but it's basically all right there, open for use. I'm a fan of the Arrow DECA which has a complete assortment of neat odds and ends. Lastly Digilent's Arty and CMOD series are awesome depending on what you need.

I know this makes a few assumptions on what you mean by "Cheap", but I find sub $200 for FPGA boards to be pretty affordable when compared to the gamut.