Well, not all 50 people drink coffee, but many would drink more than 1 cup per day, so I figure ~50 cups per day (especially once you get really good coffee in there). Imo, you need a commercial rated machine, which will cost over $1k.
This would be the top choice, and way above your stated budget, but...it will outlast and outperform other options. Yes, it's $2700 or something, but it's a beast, and would likely require very little care and maintainance for some time.
A more typical option would be this:
And I can see if Astra can give me a deal for you, but I think theirs are significantly more than the above two options. I will ask tomorrow.