How much does it cost to etch your own PCBs?
I often make my own prototype PCBs at home. I made my own UV exposure unit for about £20, and use a cheap HP inkjet printer with Mega Electronics (UK) Jetstar Premium film for the transparencies and Mega's FPC16 positive resist pre-coated boards, developed in sodium hydroxide solution and etched in ferric chloride. The FPC16 costs about 1p a sq. inch, and the film costs roughly the same. I can make a PCB in about 30 minutes (not including drilling), and can do 8/8 mil tracks without any problems.

Join the Homebrew PCB Yahoo group if you need more information on the various techniques that are available.