What you're actually trying to do is known as price discrimination. In other words, you want people who value the spaces more to pay more. Airlines, for examp

What you're actually trying to do is known as price discrimination. In other words, you want people who value the spaces more to pay more. Airlines, for example, do this by charging more if your trip doesn't span a Saturday (since that means it's likely a business trip and business travelers tend to be willing to pay more). Grocery stores do it with coupons (by your willingness to cut out coupons you reveal yourself to be more price sensitive). More generally, companies often do price discrimination by offering two tiers of service (like Windows Professional Edition vs Windows Home Edition, or whatever). So you'll have to come up with something like that. None of the auction proposals (Dutch, M+1st price, whatever) will do it because everyone will pretend to be poor. PS: Student/senior discounts are another classic form of price discrimination (the assumption being that students and seniors tend to be more price sensitive).