For me, the GS Vette is WAY over the top with all the doodads, baffles, exaggerated flares, etc. To each his own. And I think it would be a very very very thin market for resale as well. Especially since the NCRS Corvette crowd thinks they're an abomination.
Superformance | Corvette Grand Sport
Not sure if you're considering the Coupe or the Roadster, but neither does much for me and I owed a '66 Corvette 427 Convertible for a very long time.
I do really like the BMW Z8 idea. ALOT. Too bad it's outside the price range.