Then I can't plug Digilent enough. They have two very large FPGA boards available for very keen prices. The first is the Xilinx XUP, which is a XC2VP30 Virtex 2 Pro with 2 405PPC cores. This board supports DDR and is a great way to get started with prototyping Gaisler SoC designs. The excellent academic price is only $299! One word of warning: this board doesn't have true SATA ports depite there being connectors and labels saying SATA. They are high speed digital data links that are SATA like but are SATA non-standard and cannot connect to a SATA HDD. No out of band signals.
The second is an uprated ML505. This is identical to the standard Xilinx ML505, but it has a much larger FPGA on it (XC5VLX110T) and comes with a JTAG programmer. The ML505 from Xilinx doesn't. Total price $750.
I have hunted about and the prices here end up hundreds of pounds less than full commercial prices. In the case of the ML505 it is about £300.