I will be porting my code to the Bridgelink FPGA and the Cairnsmore5.  However, be warned that the lower-cost FPGA's have some pros and cons:
PRO -- the low cost FPGA's can sometimes mine core-heavy algorithms at better ROI than the high end cards
CON -- the low cost FPGA's can't mine memory intensive algorithms (no equihash variants or cryptonight variants)

Right now in terms of availability
CVP-13 $6000 available now
Krunchlabs MA-X1 $3650 available Dec 10
TUL BTU9P $3599 available now

Full list:
http://zetheron.com/index.php/supported-hardware/

The current dip in the market is pushing more GPU's offline and GPU farms out of business, resulting in global drop in nethash.  This will eventually be good for FPGA's especially when the market rises.

The latest profit table was update a few days ago:
http://zetheron.com/index.php/fpga-performance-profit/

Keep in mind also that several big coins are seriously considering new algorithms specifically designed for FPGA's.  These would likely run very well even on the low cost cards.