If they actually do what they say they do, their quality is probably pretty good. $650.00 for a vinyl front bench seat is not inexpensive. Why not let a local upholsterer do it, it probably won't cost you any more?
What car are these seats from? Do you have the old seat frames and any of the old seat covers? If you do, re-pad the seats, and do not buy the seat re-padding kit from them. There are much better ways to pad a seat than with cotton batting and burlap. CLICK HERE
to see how to do it with modern materials.
For $700, I'll do a front bench seat in 100% polyurethane (like Ultraleather) any way you want and re-pad the seat in the process. Then it will look like this. The first picture is the rear seat. The front seat cover was almost nonexistent.