I don't know if I'd go for them providing the bird, too much lack of control over the final product. If they give you bad meat, spoiled or just poor quality, it will look bad on you for no fault of your own. It also puts out there what appears to be your exact profit, few people are going to calculate your cost of fuel, seasonings, etc.
The idea of offering turkey breasts is a good one IMO. Those are pretty popular around thanksgiving from what I hear.
\m/ Heavy Metal BBQ \m/