If you want value for money, try the Knights of Dice Tabula Rasa range. You probably want to do some surface texturing ( that's kind of what the range is designed for) but the buildings are great and well thought out in terms of design. Quite good fun putting them together actually.
Of course, if you want the generic wargamers trope of square or oblong, flat roofed, adobe box, then it's as easy and much cheaper to make 'em yourself using foam/balsa/cork or even cardboard boxes and some spackle.