How Do You Transfer Lion's Ownership if You'll be Selling your Mac?

Hi. In the future should I sell my iMac it might be a hassle since Lion is tied to the credit card I can't give my account password should the buyer need to reinstall Lion. Even if I sell it with Lion I can't give out my account password when the buyer downloads an app on Mac App Store. Is there a way to transfer Lion's ownership so I don't have to sell the Mac with only the default Snow Leopard (the one that came with the Mac) installed?

By the way what should be the proper price for this iMac 2.8Ghz i7 8GB (memories were Apple factory installed, original), it's in good condition, everything's intact (box, manuals, etc.) and has more than 2 more years of warranty through Applecare was bought brand new. Thank you inadvance.

Gbu,

Alvin