Well I'm not sure that the price I paid for it would give you any indication of what you should give for it. But I can tell you that I had to order bits from many different places. Some came from Denmark, som from UK and some from the US. But it was only a little more expensive than buying some off the shelf PC with similar power.
As you can see from http://picasaweb.google.dk/klausmedk/SFFPC?authkey=Gv1sRgCKDHg4vry_u35QE#5435218694873365122
there is room for a PCI express card, but not much. Please also note the length of the card, as it must fit within the length of the case. With regard to height there is no problem, especially not if you remove the built in PSU and use a Pico PSU.