Came across some really awesome websites recently. And, er, some wargaming ones too!
I was quite impressed, as they offered free pdf's for homemade scenery pieces that you can just download, print out and make yourself. You've got various types of containers, buildings, and my personal favourite - cars. I think they can add a lot towards making some very impressive boards. Just get some thick paper/cardboard and glue.
I think I'll be going through these sites andprinting off a hell of a lot if stuff now for my games.
http://www.combatstorm.com/download.html
Cars, containers, sandbag walls, squad tokens, buildings, embassies, hotels etc.
http://www.toposolitario.com/workshop/
More of the 'container' types of scenery/buildings but quite clever and very useful. You also have various military vehicles that would be useful as props and objectives.
Happy hunting!