I've also considered 3D printing, but haven't been able to find a place that actually does it (or advertises how much they'd charge you for doing it)
In the UK I can only suggest visiting the FabLab in Manchester (http://www.fablabmanchester.org/
) on a Friday or Saturday.
You can use their 3D printer/Laser Cutter/Milling Machine for free on these days. (first come first served)
You pay a modest cost for materials.
You have to learn to design for, and operate the machine yourself.
You must document and report on what you did for the use of the FabLab community.
Hopefully there will be similar less-formal schemes available near you too if Manchester is too far.
You just have to ask the right questions in the right places really.