I took the plunge and bought the satnav update for my executive non premium nav 64 plate IS300h from eBay seller sergvia this week. They email you a link and you download it, stick it on a correctly formatted usb drive and update your car yourself using the activation code they send you. Worked first time and has changed my firmware from vc18100a to vc18101b. No issues whatsoever and was £89 all in which is less than half what Lexus quoted me. Latest maps too so result in my opinion