I haven't tried BOOM specifically, but if you're interested in a large FPGA that can be acquired very cheaply, you should look into the Pano Logic G2 thin client. They used to be available in bulk for $3 a piece, but those have now all been snapped up by hobbyists.

But you can still get them for $20 or so on eBay.

They have a Spartan-6 LX150 (DVI version, revB) or Spartan-6 LX100 (DVI version, revC), which are really huge FPGAs. It's by far the best deal in town if you're interested in that kind of stuff.

Google for "github panologic-g2" to find up-to-date proceedings about the reverse engineering effort.

Right now, the FPGA is up and running and outputting an image over DVI.

Do you have any idea about how many FFs are needed for a BOOM CPU?