I will never pay to pitch. I've done it before and regretted it. Those opportunities were for $1k or more. With Founders Space, its $150...which I think is only to cover the costs of the 1 on 1 mentoring before the opportunity to pitch. Its not for the competition itself.
I pitched at Founders Space in July and was one of the winners (yes, we did get some capital). I would do it again. Also, the mentoring session before hand was totally worth it. It made the difference for us to win.