Cool chip. I thought they had a new 144 pin version of this?
If it is only BGA the problem is it will cost a fortune for each prototype PCB. Multilayer boards are expensive to build and test. The program we use for PCBs costs a ton of money if you need more than 2-layer boards. For this package xray inspection is probably needed to get the chip on right. $500 is a little steep, but it wouldn't surprise me if it costs 10 times that much to produce a single working breakout board.
I was following some guys who were doing FPGA bitcoin mining, they solved the problem by just bringing 2 I/O pins to a header (they just need those for serial comm). When I heard this, I quickly moved away (not a big fan of unitaskers). Since then I'm looking for a cheap dev board which is a little more powerful than Papilio 500K. Maybe we can ask Jack's help, he had a kickstarter for BGA projects.