GWP3

Try looking at Dave Graffham's models on RPGNow or Wargame Vault - lots of variety at a reasonable cost and there's a basic "hovel" and a "coach house" you can download free. The coach house even has a variable "skin" finish so you can make it in various different looks and ways.

Try ebay, the original card buildings for Warhammer have resurfaced after many years
As I recall Mort built a set and mighty good they were too!

Now quite rare and very cheap

Arcane achitecture

CG

Sime, Quick and cheap ECW buildings....self build from hardboard(or the similar, mounting board), or stiff card or foamboard (Hobbycraft are for ever doing 2 for 1 with foamboard...I've got loads!!) and wooden coffee stirrers. Simply make a small box shape with 'apex' ends on 2 walls, from board and cut the coffee stirrers to suitable lengths and stick them to the board (using pva or instant grab no nails. ) to replicate typical timber framed 'Tudor' style buildings. You can form the doors and windows by simply framing the space with the stirrers and drawing in the frames or door timbers. You can even sketch out the designs on the board from images/photo's of timber framed buildings. You can use timber square cut mouldings to reinforce the internal corners(quick tip...use a leggo built 90 degree/corner to act as a guide to keep your walls straight and square and use rubber bands to keep them stable till the glue sets (overnight is best). Roof the finished product with board or card (replicate tiles by either drawing onto the reverse of cereal packet card, then cut to size or even cut out strips of card to replicate rows of tiles... or like me, cut all the tiles individually and literally tile the roof...long process but looks ton's better...but then I am a bit sad ). Simple black/white paint job and Bob is your preverbial relative


Sorry to go on but honestly mate, it's a simple method and quick method, you'll soon have enough for a small town before you know it and the more you do, the more your skills will improve.
JUST KEEP IT SIMPLE...Have a go, you don't have to be a master modeller

Best wishes
W-D

I found this site whilst searching for 15mm card buildings - 28mm medieval buildings on a CD-Rom! Hope this helps.

http://www.alternaterealms.co.uk/Medieval-town-cd-rom.html

Many thanks