You could try OdysseySalvage.com, Randy Bridgewater is a real good guy and has given me lots of free advice. He has a good set of web pages, and you can call him too, at 913.856.6639. I would try him first, he can get new Honda parts as well as used.
Also, I have had good luck from a guy named John Mscisz (not sure of spelling on last name). He can probably get you what you need. Here's his email address:
jstop1212@aol.com . Tell him artisanjrf (John Fickle) sent you.
If you would feel more comfortable ordering from a Honda dealer, then I'd call Hillside Honda @ 707.263.9000. They are familiar with Odysseys. I haven't personally done any business with them but tsutton44 recommended them to me. If you're going to pay for a new Honda part you may as well buy it there.
Hope this helps.