I was following the thread "Official Open Source FPGA Bitcoin Miner (Smaller Devices Now Supported!)". Unfortunately I am a newby and cannot post over there, now I do it here:
I have found a standalone FPGA board with ARM linux system incl. network that is probably not so far from being competetive in the MH/$ region:http://www.dinigroup.com/new/DNDPB_S327.php
It has 27 Cyclone III with 120K LE. From the above mentioned thread you can get a full SHA256 pipeline into ~75K LE running at 100MHz = 100MH/s.
27*120K LE = 3240K LE => 4.3GH/s
Probably with less than 150W power consumption. VHDL code is available from the other thread, as its linux, one of the available miner cores should be easy to adapt.
Price: ~21K$ :-(
The FPGAs alone should be somewhere in the range of 8K$, so there is probably potential for a price reduction, if we buy enough of the boards.
With power consumption becoming more and more important (in Germany), anybody interested in buying some boards?
Of course an ASIC solution is far superior, but will require much more work and cost upfront.