Absolutely every model is compensated in some way for their modeling time. The actual compensation varies greatly. Some models accept prints as compensation, in which case, I attempt to provide at least 10 top quality, hand printed 8x10's. Some models trade modeling in exchange for other photography projects. I also pay models for nude modeling.
Many models work exclusively for prints.
All models are invited back to view the results of their modeling sessions, or I can e-mail small scans. Typically, for every hour I spend in the studio, I spent six or more hours in the darkroom. Thus, I value the prints highly. It is my expectation that these prints are for the model's use exclusively. The prints are not to be sold or used to advertise anything other than the model's career.