We considered a similar approach with our coworking space in Brighton, UK (http://theSkiff.org). We were going try an airline ticket model. eg First people to commit to paying for a particular month get it at the cheapest price with the last desk to be filled going at a premium.

However, while we felt this might work well if we were simply selling serviced office space, we didn't think it would help create a nice coworking environment. In a coworking space the individuals that come to the space are far more important than anything else. If we made a big deal out of the pricing structure, we might end up with people that are their primarily because they see it as cheap and not because they want somewhere to cowork. We choose to just keep it simple and replicate Citizen Space's approach: http://coworking.pbwiki.com/PricingExamples