I haven't found anything that allows for a permanent sort of transaction in the style of AirBnB. It's all very temporary, you know?

This will sound weird, but I feel like eBay would probably be really good for that because people around the world are aware of it and have been conditioned over the years to expect to find anything. Even houses.

That said, eBay sucks. So there's certainly room to challenge it, but cutting into that kind of market share and brand awareness may take more money and publicity than it is worth.