I am working on a project to 3D print (models from) human hearts. I want to know if anyone has done it before using DICOM files.
I have some experience with VR visualisation of DICOM scans. I can tell you that these kind of scans usually are way too "hazy" to simply be 3D printed. To give you the best images possible you need to make a high-resolution scan of only the heart (smaller region scans make better quality images). Siemens has had some fantastic result with their new range of scanners. You also need some kind of software to convert it to a 3D model. This will need to make a pointcloud of the heart, clean up unneeded tissue and then make a polygonal model to be able to print it.
Or maybe did I misunderstand your question... in that case you need to look at turbosquid.com, thingiverse.com or cgtrader.com for example.