I don't think you will find any current FPGAs that cheap unless you buy lots of them. I bought some Altera Cyclone EP1C3T100C8 chips for prototyping recently from Arrow UK for 8.13 GBP each (plus carriage and VAT). I've often seen older devices for sale cheaply on eBay.
Something like a Xilinx Spartan IIE XC2S50 is £22-35 from RS, £6-83 from Digikey !! The Digikey price includes duty, but not shipping (£12) or a 'handling charge' (£10 if order total < £75). Neither price includes VAT.
If you wanted something a bit bigger, an XC2S200 is £42-31 (RS) or £14-11 (Digikey) !
I have had excellent service from DigiKey (and, to be fair, from RS most of the time ...)
If you don't need to get your hands on an actual piece of silicon immediately, take a look at Altera's MAX2 family. Essentially it's an SRAM FPGA with built-in config memory. The first engineering samples appear to be out, but it might be a few months until volume production. I've heard they are pretty attractively priced.
If you do not require large quantities only CPLD are available in that quantity. (Even a XC2S15-5VQ100C costs 10$ if you buy only a few pieces)
CPLDs start from approximately 1GBP and are available in the UK from digikey and other stores as.
If it is for a hobby project that does not need an ongoing supply for chips I still have a surplus of 10 pieces XC4010XL and 180 pieces XC4013XL that I would sell to you for 5GBP each. I also have software that supports these chips.
If you need only a single prototype you should buy a low cost development board from
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or one of its US competitors like xess or digilent.
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