They were over $50k when they came out in limited productions, so if you can find one for sale, I would guess it would be over 40k..
I did find one on Ebay, if it isn't a scam, it's a steal....
"IT WOULD TAKE 34500 TO PRE BUY. THANKS"
http://cgi.ebay.com/ebaymotors/Ford-Mustang-2DR-CPE-SHEL-SHELBY-GT500-STUNNING-TRIPLE-BLACK-4K-MILES-NO-RESERVE-STRIPE-DELETE-ALL-/200676486631?pt=US_Cars_Trucks&hash=item2eb9402de7#ht_66037wt_1161
I did find one on Ebay, if it isn't a scam, it's a steal....
"IT WOULD TAKE 34500 TO PRE BUY. THANKS"
http://cgi.ebay.com/ebaymotors/Ford-Mustang-2DR-CPE-SHEL-SHELBY-GT500-STUNNING-TRIPLE-BLACK-4K-MILES-NO-RESERVE-STRIPE-DELETE-ALL-/200676486631?pt=US_Cars_Trucks&hash=item2eb9402de7#ht_66037wt_1161