Re: Cheap FPGA ?
As Xilinx says in its new Spartan 3E family of volatile FPGAs there are neither bells nor whistles, still it is the cheapest FPGA from this vendor. 100K gates FPGA shouls cost you about $2 in large quantities.
Another option is a nonvolatile ProAsic3 from Actel. They say it should sell for under $2 in volume for 100k gates devices. The problem is that Actel is not shipping the stuff yet.
FPGAs from other vendors ( Altera, Atmel, Lattice ) fall within more or less the same price range, so the factor which really may influence your choice is not the price. Try making your decission based on the development tools, internal architecture, supply voltages, availability, etc.
regards, yego