Neil - Shapeways sells 3D printed items designed by 3rd party designers (such as myself).
They are a bureau for designers - a shop window if you like. Shapeways prints the parts and sends them to the customer who has ordered through the Shapeway site and then a percentage of the part cost (not postage cost) is passed on to the designer.
I use Shapeways for the 3D parts for our kits, but these parts are not on general release, meaning that you cannot buy them from Shapeways - only I can.
Yes, the postage can be a tad eye-watering at times - and if you saw the size of some of the boxes they package the parts in it might go some way to seeing why. The parts are certainly not heavy so it isn't a weight issue. I think it is more a physical box size issue - they use, what at first glance might seem, un-necessarily large boxes....but when you open the box, you can see all the safety packaging that is used to protect the, sometimes, very delicate parts.
I would challenge even the most Neanderthal courier driver to break the contents!!!!