Would they sell the house to you?
Often it's easier for an owner to work out a deal with someone living there already--no showings, no fixing up things, you already now all the nuances of the home..
If you can get a mortgage for the 80% and they'll carry the 2nd that might be a good option.
Also, sometimes banks will allow you to transfer the mortage to a new owner, but in this case you'd likely have to comeup with a large down or find a 2nd mortgage.
Then, you don't have to move, you own something and you can continue hosting and leveraging the built up reputation you have in your listings.