I loaded your X3D file into MeshLab, it shows 450,669 vertices and 901,342 faces !
I have done a 'Quadratic edge collapse decimation' to reduce the number of faces in your model and attached the file.
This reduces the count to 56,331 vertices and 112,666 faces.
You may want to look at the model yourself to make sure it is still what you want, but it looks fine to me. Far more detail than I think you'll get out of the 3D print.
I tried uploading and it worked fine, shows the bounding box as 5.9cm x 4.7cm x 5.0cm and priced at $27.95.
I've saved it as an STL file. When using Blender I have had problems with X3D files with more than 50K polys. I don't know if it's the Blender exporter, Shapeways importer or something I've done wrong, but STLs seem to work when X3Ds don't !
Regards, Ian.