I’m mindful that we are using a self-hosted system (for various stupid internal political reasons) but that I’m posting quite a few bug reports and ui suggestions on this forum. I absolutely love Discourse so far and our (quite slow, staged) rollout is going quite well. I just wish (as a large organisation) there was some way we could be supporting development a little without paying for hosting.
I realise this is a tricky thing for FOSS projects, and I really wouldn’t like to see you change this community or move to a model where non-paying users can’t get your great support or damage the community feel here.
I suppose what I’m suggesting is a ‘institutional subscription’ which sounds good enough to get companies to pay for so we can support you, but is basically optional doesn’t make a huge difference in practice 
I know in theory we could just make a donation, but that’s impossible to get through finance departments. I’m not sure what you should call it, but I leave it here as a suggestion. Perhaps it would involve an SLA for a response on this forum and special or tailored security advisory notifications?
In terms of $ amounts… a one-off payment of $500-$1000 is probably in the sweet spot of ‘not too large to be a pain to get through procurement systems’. Actual annual subscriptions/contracts are more complicated, at least for public sector or educational institutions, in my experience.