iMakr opened a large 3D print retail store in London earlier this year. The store sells various types of 3D printers and offers the public a chance to see the technology first hand.
Even though they haven't been open very long, they've now added a new service: 3D prints on demand.
It works in a simple manner: bring in a 3D model (presumably STL format on a USB stick) and their staff will inspect the model to ensure it's printable. Then if so, they'll print it off on one of their Up! personal 3D printers. If you cannot physically get to their location, you can email your model instead.
There's no word on pricing for this service, but they say it will be "affordable".