I went with Advanced Keys (
http://www.advancedkeys.com/) and just finished the install.
This is a very well designed and thought out kit and the technical help team is great about responding in a timely manner to e-mails.
It uses RFID and it'll integrate into existing alarms, power windows/door locks, allow for remote engine start, remote trunk opener, etc. It also had generic inputs/outputs to allow you to customize functions. Example: I used a generic "ground when armed" circuit to facilitate a fuel pump cutoff circuit... I walk away from the car and the system automatically disables the fuel pump.
The only thing with these keyless start systems is you have to address the column lock if you want true keyless start. I ended up eliminating my column lock (took the plate out of the column and ground the "teeth" off of it). With my anti-theft features, they'd have to tow the car if they really wanted it that bad, so column-lock or no, all bets are off at that point.
The set up comes with an OEM Lexus button too...
Here's a short video of it operating...
https://www.youtube.com/watch?v=8THLF...ature=youtu.be