I dled Blender, which is freeware, a week ago. Its interface used to be pathetic, but now it is a lot better, at least livable. In a week i managed to learn most of the basics (although i had years of experience from other 3d modellers). So if you want to learn how to model in 3d without paying anything, you could try it :)

Here is some of my stuff these days:

http://i.imgur.com/5uJRz.png

Blender is a very powerful tool, but takes a lot of practice to learn. I've used it to mod Morrowind and Oblivion armour, and it works well. It used to take a certain amount of patience and luck to get the correct Python installation working with niftools to mod the latter.

Nice buildings btw :)

I am sure it does, but it is a good modeller so even with basic knowledge of it you can create something passable (like those buildings) :)