I recently purchased a 2006 A3 quattro and I'd like to purchase a USB vag-com interface cable to be able to clear and check codes, service reminders, etc. When I look at the cables available on ebay, it appears that most are not compatible with my car. The vag-com web site says that 05 and latter are considered A3(8P) which is not compatible with the $20 cables you can find. Does anyone have advice clarifying exactly which cable I need and where to get a "cheaper" version than what's available through vag-com?