I just found this service which provides very inexpensive PCB’s for hobbyists. His pricing structure is very simple: $5 per sq inch, you get three copies of the PCB, and there’s no setup fees and free shipping. He’s doing kind of a BatchPCB thing, but somehow has made the cost less expensive. (BatchPCB is $2.5 per sq inch, you get one copy of the PCB, and there’s a $10 setup/shipping fee). I haven’t tried it yet, but he says he needs more people to use his service, otherwise he loses lots of money, so I think I’ll give it a go.
Oh, and did I mention, it’s with 6 mil minimum trace/spacing?