Mostly echoing what others are saying here. When I deliver a wordpress site to a client, there is no way I am going to include pirated software. I don't want any sketchiness finding its way back to me. Also, I will pay for any software/plugin/theme that costs less than my time to build the same thing. It's just a matter of numbers. A $35 theme can get me 80% of the way to a client's desired layout. If I'm getting paid $500 for the project, then I'm making $465 for only a couple of hours of work, rather than $500 for several hours of work (starting from scratch).