The White Towers are still available made-to-order, and the resolution is the same as Shapeways FXD. What I could do is upload the STL to Shapeways and see what the cost differential would be. It certainly would be much easier for me to have the product available through Shapeways than through the current process.
The PD4501 Scenicruiser or any GM bus won't be going up for sale through ESM because 1) they have to be licensed through GM and 2) CMW currently holds the HO and N license for the Scenicruiser. Given that the CMW owners are N scale modelers, an N scale Scenicruiser will appear as soon as they figure out how to make the ROI reasonable.