Which DSP Dev Kit and ADC module should I buy?

A quick search of the product information shows that TI manufactures 17 active A/D converter ICs with 12 bits of resolution and sampling rate limits of 105 to 250 MSPS, typically with LVDS output.  They have evaluation modules, e.g. ADS4125EVM, but these modules are usually compatible with the deserializer TSW1200EVM (which is meant to interface with a TSW1100 analysis tool or with a PC) and *not* ready for direct attachment to DSP Starter Kits.

I suspect that even with the fastest TI DSPs, you'll have trouble sustaining Fourier transformation at a rate of 100 MSPS, especially if you need to send the result somewhere, and at any rate you'd need to adapt the A/D EVM to work with the DSP in parallel output mode, since there is no way the TMS320Cxxxx DSKs can process serial data at a 1200 Mbit/s rate.  (I don't think you can even route signals of that frequency reliably thbrough the inter-board connectors.)  There are several slower A/D EVMs designed for use with DSP Starter Kits via the 5/6K Interface board, e.g. ADS7863EVM (500KSPS).  There is also a THS1206EVM (6MSPS aggregate, 2 or 4 channels) with parallel output instead of serial output.  You might consider whether you really need to operate at such a high sampling rate, and if you do, perhaps instead of a DSK you should use the ADC_EVM->TSW1200EVM->PC setup to store and analyze the raw data on the PC.