It's a cool idea, but with Borders barely surviving I think most customers are lucky they get any kind of coupon!
Seriously though, as a former Borders employee I will tell you that a) Borders is most definitely a slave to their bottom line, and b) they have a history of trying to chase what's cool and new. If you convince them ebooks are profitable AND it sets them aside from B&N and the used bookstores, then they'll take it seriously.