This appeared originally as my answer to a question on Quora, which can be found here: Should I pay my models to model for my fashion line I’m trying to start?
If you were a model, would you want to be paid when modelling for some company/startup? All successful startups’ founders ensure that their stakeholders (employees, freelancers, investors, etc) are fairly treated and compensated for any work they do for the success of their firm/startup. So, if the models are going to be modelling for your startup, they should be compensated fairly for their work. That shall help build your reputation as a fair leader, and make those models spread around good vibes about your startup.