Is it too much to expect..

Real question.... I help run an annual fund raising event in Brooklyn and our great DJ from last year has moved out of town. We are all volunteers, and no one gets paid. Is it too much to ask an experienced DJ to work a four hour event for free? 

What makes our evening unique, is that we celebrate the music of a single artist, so it’s definitely a specialty playlist. 

I appreciate any thoughts or recommendations.