That's too bad, Mark. Mostly the loss of time invested and that you're back to searching for a singer again. If it hasn't unraveled totally and if your mates are open to it, maybe a compromise could be worked where the singer buys part of the pa?... He gets the speakers, someone else (or even the band splits) the board or something. Just a thought. Could be that financially your singer just can't swing it at the moment regardless of his intentions to do so. I understand your view of the investment instrumentalists make vs vocalists, although it's unusual (in my limited experience) for the singer to own the whole pa unless a band leader that's hiring side players. Instrumentalists can gig with a small investment like a squire classic vibe and blues jr... even thos we'll gravitate to the best gear we can afford.
Other thought is to look to clubs that have their own pa - most around where I live have their own system now, which of course makes it a lot easier. Anyway, hope this bump in the band road works out for you.