Perhaps some of the dealers could make up a current price sheet for each of the models they sell, updating when new models added. That way, it could simply be attached to a reply email when an inquiry is made regarding Omega, for instance. Repeated email inquiries for additional prices could be avoided, and a dealer could send out updated prices to previous customers in a bulk email periodically.
The only inquiry that would be necessary would be to check current availability, and since price is already known, and accepted, a higher percentage of inquiries would lead to sales. Initial inquiries wouldn't drop, but eventually email maintenance would lessen from the dealer's perspective.