I don’t have experience of buying bulk – but i do have experience of trying to maintain them all.
Tell the folk that want to spend 200 per bike that they’d be better hiring for that money. I’m all for value and in fact pay as little as i can for my own bikes – but i’m quite happy to spend say hour/week keeping my own bike in condition,
bikes used by more than one person, used by kids/beginners, cheap bikes , bikes carried together on trailers get and bikes stored in space that’s not really big enough/dry enough – they all get trashed, put any of that together and it’s a nightmare. (in my own case it was all of the above)
The insurance implications for a charity could be pretty dire – so all bikes need to be in 100% condition all the time – that will be easier with a no nonsense but slightly more expensive bike.