If its for a campaign, you may want to establish a team, with a set team and an announcement of your progect, you may have better results in adaopting model makers. Having one's name associated with a big-name campaign would be very good...
Other then that, yes, model making is hard and if modelers have spare time, they'll usually indulge in their own ideas, for they are a bit more rewarding for them.
-VGsatomi