I'm in the middle of a similar transaction right now. Bought a set of rims (used) from a seller on here and had them shipped to a shop in buffalo. Bought tires from Tire Rack and had them shipped to the same shop and installed on the rims. Seller is providing a receipt for much less than I actually paid for the rims, and even paying full tax on the tires they are still hundreds less than what I could have bought them for here.
Picking them up this week, will update on how it goes.