Sounds like you did your home work.
A tip for saving money on a new master key. Members of the Lexus Owners Club recieve an excellent discount on Lexus parts from a dealer in Dallas, Tx. The dealer is Sewell Lexus. To contact them go to
" sewellparts.com". When you log-in, there will be a section where you can enter your membership to the LOC.
I lost one of my fobs in August. the local dealer wanted $320.00 for a new key with fob and programing.
I went to Sewell and got the part for $162. Let us know how things turn out