Troy,
They are a reseller of Vintage Speedsters, the photos on their site are of the Vintage Speedster shop in Hawaiian Gardens CA. One of the photos on the front page, is a photo I took of a Vintage Speedster. They look like they order directly from the factory and resell. JPS on the other hand uses Vintage Bodies, but actually assembles the car themselves.
Take a look at the Makers section in the top menu here. We list only manufacturers, not resellers. If you search the internet you will find many, many different "356 creators", they are all selling a Vintage Speedster manufacturered car. Some are very up front about this, many are not.
Seats are an option, there are a few different styles with all the manufacturers.
Oh, and this is really funny. The following picture appears on their site. The guy in the background is wearing a Vintage Speedsters logo T-Shirt.
www.356speedsters.com/images/facility/IMG_0646.JPG
-=theron