Amongst my other sound gigs, I provide the sound/lighting production for three yearly "non profit" events in my community. My personal tech services are invoiced as "free" but there is a fee for my gear rental.
When the "non-profit" calls just tell them that you'll tech the event for free (an important word) as long as the gear (that you spec) is provided (rented/installed, etc.). You give "your rider" to the promoter and steer him/her to whom to rent from and the promoter will call you back in sticker shock....
Tell the promoter that he can rent the gear from you...for a negotiated price (even 5% less than the local rental house).
The gig is yours.
Mike M