Hi there,
I don't think you can find anything with the specification you mentioned for that price.
If you are looking for an FPGA board with an FPGA better than the one you mentioned, you have to pick your options or end up paying at least $1200 for such a board.
One good compromise will be the Xilinx/Digilent XtremeDSP Starter Platform – Spartan-3A DSP 1800A Edition **broken link removed** which is $295 but does not have ADC/DAC, but they can be easily added using the provided and supported SPI interface.
It has :
XC3SD1800A-4FGG676C Spartan-3A DSP FPGA - which is a much larger FPGA
128 MB (32M x 32) DDR2 SDRAM - For data storage/program code
10/100/1000 PHY - For high-speed communication with the PC
4 SPI select lines - To connect to your own ADC/DAC board
Low-cost VGA - For display your data
Hope this helps,
Best regards,
/Farhad Abdolian