"Custom" anything is usually worth less than the same item would be if it were stock. It's simple supply and demand. Yes, the supply is low, but the demand is virtually zero.
Young and enthusiastic kids find this out the hard way every day when they try to sell their custom truck/Jeep/whatever that they have tricked out with all kinds of expensive aftermarket stuff, and find out they are going to get about 10 cents on the dollar for all that nice stuff, instead of the $1.10 they thought they were going to get.
Unless you happen to find just that one right buyer, I suspect the value of those seats is pretty close to trash.
