I think somebody has already mentioned it above, but you need to get a SEWELL account. It's free to sign up, and you get a huge discount on OEM lexus parts. If you want FACTORY parts, this might be one of the cheapest options.

There's always nice aftermarket performance parts out there, but as far as non-performance stock replacements you dont get much better than Factory Toyota parts. Sometimes cheaper is not better when it comes to "replacement" parts.