I worked for a communications test gear maker for a while and they built a unit that used the top Xilinx part at the time at a price tag of $1.5k. The unit sold for over $100k so they weren't too worried about the FPGA cost. In fact, they were using less than 20% of the chip and just wanted the space for "future expansion".
BTW, they only expected to sell some 10 of these units.
Rick