Max for min---From our board house we can get as many boards from a piece of 200sq inch board. Sometimes it's cheaper, sometimes it's not. There are also some cheap proto houses out there also. You can get a proto as low as 3 boards for $100.00. The max for min for us is about $500.00.
Here are a couple of proto places
http://www.zoompcb.com/fast1.cfm
http://www.pcbnet.com/
Thanks,
Craig