I've got this:
http://www.fargo3dprinting.com/buy-3d-printing-supplies-bitcoin/It may help you.
and I don't think there are any big and known shops accepting bitcoin to purchase something. you can buy 3d printer part from ebay and amazon and for make payment through bitcoin you need to get help of some ebay or amazon re-sellers.
I saw some peoples offering their amazon reselling service in digital good section.
take a look there.
The issue with Amazon and Ebay is they their always low quality clones, at least for 3D printer parts.
