I made an order with Tom Scheid of NKP Car a few months ago, which included some Train Station Products passenger car core kits.  I asked about  an out-of-stock TSP product, and for contact information so I could get in touch with TSP directly, but Tom said that the owner at TSP "doesn't like to be contacted by customers."  As far as I know, there is no way to order directly from TSP.  I'd suggest getting in touch with a company that supplies TSP products to help you out.  From what I could tell, TSP is still manufacturing product.

Dan Miller