We did something similar to what you are asking for a client of ours that had a venue to promote. We set it up so that various customers could sign up as afilates and then place a custom link on their site. Everytime someone clicked on that link and came to the site and ordered tickets a small amount of the proceeds was kicked back to them.
You could possibly do something similiar but rather then money you could do some sort of top dealer program where you track incoming from each link on the retailers site and then either pay a small amount of money to the top 3 or rank them by Bronze, Silver and Gold and then send them certificates that they can display in their lobby at the end of the year. This would encourage them to link from more then one page and in more visible locations. I know your probably, mostly after the links but this would make it easier for them to swallow cause they would feel like they got more to gain.
Another thought would be to give the top three links off your home page. Turn it into a bit of a competition. You could change these links out each month based on the traffic that the retailers send back to you. If you used a small graphic as part of the link this would be great for promoting the brand and the competition would tend to push your link placement to the top of these retailers pages. That equals more brand recognition.
