I have a range of the houses and ruined houses from these guys (before they were bought out).
https://www.timelineminiatures.co.uk/store/index.php
They are pretty good and will certainly bulk out your table for more expensive centrepiece buildings while still looking good. Reasonable interior and exterior detailing which can be improved on without too much trouble.
Edit: although on looking now, they have a larger range but don't sell two of the house types I was thinking of which were very cheap and looked great for fantasy/historics...