I did customer development around a similar idea in London and discarded it. End users (desk seekers) want it, but it's a marketplace and the value proposition for desk sellers is more troubling.

You get useful postings in 1 of 2 ways:

  * You keep the data fresh yourself
  * Office managers keep their own data fresh

In the former case, you need to be making money to continue spending the time beyond its novelty period. In the latter, the office managers need to be getting good value-for-time or some related benefit which is enabled via their site activity.

Of the potential problem office managers care about, you've got:

  1. Dealflow & advertising
  2. Showings & deal closing
  3. Dealing with current tenants

#1 is adequately handled by craigslist/gumtree. I thought it would be a pain point, but the office managers disagree.

#2 is a huge pain, but you can't resolve it without manpower that would require a much more profitable business model than exists here.

#3 is the most promising, and is a legitimate pain point, which is where I decided the most plausible business lay. If you can handle the billing for office managers, then they'll put their desk spaces on your site to be saved the problem of hustling tenants for payments. There are liability issues here, but it's probably a similar model to AirBnb.