It's really pretty simple. You can make calendars from snapshots at Walgreen's or any of the online photo places like clarkcolor, snapfish, shutterfly, ofoto. I don't know, but it would probably be more cost-efficient to find someplace that would make them in quantity.
The 'rumfie club here in STL did a 2006 calendar. Had the women posing with cars for each month. Was pretty cool actually. I can talk to Kathy and see where they had them made up.
Problem is, with over 5000+ members and more than a dozen marques, how do you decide whose car/what car to feature? One marque for each month would be the best way to go.