I think finding a willing dealer will be much more difficult then finding the last company such as visual garage or any third party for that matter. Most dealers seem to stray away from online business for parts.
If the dealerships only knew what they were missing. A dealership in Texas (Sewell) has pretty much become the defacto parts dealership for clublexus which has 145k members. I know they do huge new/used car business because of referrals from the site as well. They have been very successful by offering group buys and specials targeted at forum members.