They didn't charge me a damn thing extra for it
On their website it shows the superclocked edition is just $10 more than the regular version though.
I've got the card at 696/1566/2494 which is about a 10% increase from stock now and it's running great. Not gonna try and push it any farther as it meets my needs now. I've also got the fan running at 100% and I don't find it very loud at all. Maybe I was use to my 7800GTX 512 fan or something.