Does it need to be an OEM part?
If not, I've boughten a few parts that are made to OEM specifications, but aren't manufactured by the OEM supplier itself.
If that's fine with you, try:
www.autotoyotaparts.com
This store does sell a few OEM toyota parts, but they also sell parts that are made to OEM specifications b/c they're generally cheaper.
I bought a radiator from them one year ago and thought they were very professional in handling my order. I received an e-mail confirmation of my order, an e-mail of the tracking number, and when my first radiator was damaged by UPS, they gladly sent me out a second unit and with no-hastle credited my account.
Highly recommend them.