Here is guidance from Lolth:

“On the main streets they were 5 or 6 silver per tile, on the back streets 3 or 4. I forget if it was 4 and 6 or 3 and 4. I would err on the higher side. They were intended to be a coin sink.”

We charge for tiles on a per floor basis, as a two or three story house is more space and should be more expensive. Ballpark: A smaller house might be 40s, a larger home upwards to a 1g. One of the biggest homes in Mythmoor, Perry Manor, cost me 1.2g or 1.3g, if I remember right. Lolth sold it to me. Average house size is in the 60s range. Ultimately, the price is negotiable and up to the GM.

Lolth:

“Also any player who has been absent 6 months or longer you can take their home back, the only exception I ever made was with past GM’s, I left theirs indefinitely.”

Thus far we typically only revoke ownership if a player is interested in a home and the current owner hasn't logged in for a long time, but again it's up to the GM. I know I have had at least one player come back to find their home owned by another player, and I had to set them up in a new home.