Hovels is a great source for hand-painted 6-25mm resin
Total Battle Miniatures makes a wonderful line of buildings in
an assortment of scales, and they are available "painted."
Gamecraft Miniatures has the largest selection of Middle
Eastern Buildings in 6-20mm. Allen's service is also top notch.
Elhiem Miniatures sells beautifully sculpted WWII and
modern day miniatures in 20mm.
Timecast Models produces a beautiful line of 6mm resin
buildings suitable for WWII.