However, the way you suggested is automatically unfair. You're assuming that a richer person will want to pay more (and they will) but that they won't feel unfairness when poorer people get a better deal. Unfortunately, even if I was rich, knowing the person next to me was getting cheaper rent just because they were poor (or less successful or less hardworking) would seem unfair.

You might want to offer different services or spaces for different amounts, cutting back costs and offering cheaper/smaller space to make the inequities real, and therefore justifiable.