If you are wargaming on a budget most MDF buildings will be too expensive to have more than a few. I recently bought a set of buildings from a small independent manufacturer selling on eBay which were excellent value for money. The details are basic but with a good paint job, they will enhance any wargames table at a fraction of the cost of other commercial products.
I don't often single out a manufacturer like this (and no, I'm not on commission!) but these were such good value I had to do a video to show them off.