So, in the words of a great man, "I ain't got too much money. No sir, not too much money at all." But I am undeterred. In fact, I find the process of creating terrain and models out of junk on the cheap actually adds an extra element of fun.
With that in mind, here is a building I originally made as part of Roebeast's Trash Bash, which has outlived the rest of the project. The body is made of three layers of packaging styrofoam which I scavenged out of a dumpster at work (I work in a hospital pharmacy, and we throw out a
lot of foam packaging). The dome and roof are a blister pack from an Androidz toy which I bought in Poundland; I roughly cut the foam to the right shape with a utility knife, then hid the joins with several layers of polyfilla mixed with PVA glue. Doors are scrap card and the decorations come from surplus decals (a Soviet bomber, if I recall correctly) and signs printed from toposolitario. The radar dish came from another Poundland toy, which also provided missiles for one of my HotT armies and an APC for my sci-fi guys. Total cost of materials, therefore, is probably something like £0.10.

So, as you can see, it is not the world's greatest piece of terrain, but my priority is generally to fill a tabletop quickly and cheaply rather than to produce works of art -- that's what my schedule, budget and gaming habits dictate, and frankly I don't think my talents lie in the direction of detailed modeling anyway. I don't have the patience.