Found this. All the info you need on the car. Seats are Cobra:
It appears this is not the first time this car hit the market. A quick Google search turned up that it hit Ebay back on 2007. It also appears that it isn't the first Overhaulin' car that has hit the market either.
There are several theories as to why people are selling them, financial, publicity, storage, etc. I guess it's one of those be careful what you wish for types of things. A blessing at first then a curse. Who knows.
The quick research that I have done states that the following cars have been sold since they appeared on the show:
1971 Torino GT w/351C & C6 (formerly owned)
1970 Convertible Boss 302 Clone w/302 & C-4 (formerly owned, now resides in the UK)