GameCraft Miniatures have budget terrain available for 15mm,1:285th scale and 20mm gamers.
From their announcement:
GameCraft Miniatures have launched some exciting new product lines for gamers that want great looking scenery that does not break the bank and assembles in a hurry. For the 285th scale gamers there is a whole series of buildings constructed of quality mat board. These mat board buildings come on European style and middle east style buildings and come in ruined and non ruined versions. For 15mm and 20mm gamers there is are new foamboard buildings that let you put together a large city quickly and on a budget.
For more info on these new lines of products please visit our website.