In the “for what it’s worth” department…
At this time of year Wal-Mart sells cheap undecorated plaster of paris buildings (for Christmas villages) in their crafts department. ($2.88 each). I have a bunch of them on my layout. They’re a little cheesey “as-is,” but I cut the base off (I just use a miter saw – makes a mess but it’s easy), and file off the trees, wreaths, misc. unwanted stuff. Although I’ve done no careful measuring, to my eye they are near HO scale (after the bases are removed), and HO scale people look just right at their doorways.,
Being plaster, they’re great to light (no glowing walls), and easy to paint and weather. I get a kick out of 'em. Can’t beat a building for under 3-bucks.