We have not quite figured out how to limit online sales to only those folks too far from a dealer. The bottom line is that we don't want to cut our dealers out of their fair share of sales, after all they are at the front line for keeping our customers satisfied.
Take the orders using forms + php,asp whatever mid tier app lang your using pump them into rdbms (sql).
Create a sso openid system for retailers where they can log in see their open orders. You can assign them from the db based on location, round robin, inventory, schedule, many possibilities. Provide customer with feedback from dealer,retailer notes.
Control the routing and monitor service sla and you will control quality and customer service.
yanche hit it on the head, in our group i do most of the architecture, programming, database but all the design, human factors is done by my partner.