If you are interested in going into the kit business, Jameco has a service for you. The process for getting your kit made is simple. You submit your kit idea to their forum and if it gets enough votes Jameco will go into production with your design. Kind of like Kickstarter. They are partial to parts in the Jameco catalog of course, but it is not a requirement. If you have the Gerbers for a PCB you can submit them as well.
They are working with PCB manufacturer Bay Area Circuits which has some good deals for small volumes. They charge $125 for as many PCBs as you can fit in 90 square inches (for a single design). And they will throw in a T-shirt that advertises your genius as well. They can do 3/3 (trace width/trace spacing in mils) if you need it and vias down to 4 thou. Amazing. Have a look at their capabilities page for more information. They specialize in speed as well as tight tolerances so if you are working in industry they appear to be an excellent resource.
On a related note I came across a page with listings of a number of PCB services. It includes free schematic capture and free PCB layout software along with paid versions. It also includes a number of different board services that are at least somewhat hobbyist friendly.
One bit of warning if you decide to use the DorkbotPDX board making service. I submitted some small boards (under 1 sq in - one was .525" X .550" ) and priced them out according to their rules and instead of telling me there was a minimum charge for boards they said nothing to me for 10 days despite repeated e-mails. For another board (3 sq in.) I did give them an excellent review here. I finally figured out at the end of the 10 days that they weren't going to deal with me. That was not very nice. At all.
I don't mind that they made a mistake in the way they priced their service. I object strenuously that they didn't at least tell me they were no longer interested in my business. I still haven't received a response from them - a month later. So if you have some very small boards ask them first if they are interested.
BatchPCB was much nicer to work with and they do have a policy for small boards. You can also pay a little extra to expedite the service. When the boards arrive I will write them up and let you know how that part of the project (a microprocessor development board) went.
M. Simon's e-mail can be found on the sidebar at Space-Time Productions.