@Michael, it's not just the IP: you're going to need a "High Speed Serial Connection". The humble [cheap] Spartan-6 isn't good enough; according to Xilinx you need at least a Virtex-6. Remember to factor that into the price.
Throw in stripline / microstrip effects for data clocking in the GHz, and I DO fear JESD204B is not for me. I'll use slower clocks, a parallel output, have a cheap Spartan-6 FPGA within 5cm (2 inch) and try to match trace lengths.
High speed serial may be deisred for specialized applications. However, it may introduce new set of problem. Does fast edges of this communication link compromises performance of high resolution precision ADC and DAC.