O-B Chris C. had a membership in something called the Triad Group that beat the appliance prices he found elsewhere by hundreds of dollars. Check for buying privileges offered at your work, or credit union, or by a membership discount retailer. As always, get multiple bids for your items.
It might also be possible to form an informal buying club with other owner-builders with whom you network. (SeeOwner-Builder Connections
on our website to find other O-B’s in your area.) By buying quantity of almost anything from lumber to appliances you may get a bigger discount on a competitive price, or earn referral fees on say, financing, that you can share with your collaborators. The idea is to get low prices without paying a fee, merely by buying in volume. And you have built-in volume when you build.