I think the houses cost the same as before but you get more coins in 15h but still this makes it a very unattractive option to buy the houses for either income or XP. Have a feeling that because reaching certain lvls in CSM is part of the new goals offered in some TL games, they've done this to prevent someone from just sitting around for a couple of hours collecting XPs and levelling up in CSM to complete goals and get gems.