I haven't purchased one, but when I was checking around, I saw www.autocomputerexchange.com had a rebuilt one for $295.
Thanks for the website. I always need to know my options before a visit to a $$Lexus$$ dealer.They are the only ones who will tackle the "electronics", and in Canada I think they double the prices!
www.autocomputerexchange.com is a great place for an ECM. Replaced mine a year ago through them. You send them yours, and they send you a rebuilt. The $295 includes next day shipping from them. You can actually install it yourself (just unplug the old and plag in the new). It is located under the carpet where the passenger puts their feet - need to rmove the trim panel under the clove box - will save you big money ($1,200 for ECM and another $300 for labor). And if you need tech support these guys are on the phone, walking you through it. Better waranty than a dealership.
Cheers,
Greg