There are free modelling apps all over the place.
Here's links to a few of them:
http://www.wings3d.com - Wings3d, polygon sub-division modeller
http://www.anim8or.com/ - Anim8tor, pretty simple sub-d modeller and animation tool.
http://www.metaseq.net/english/index.html - Metasequioa, haven't used it.
http://homepage3.nifty.com/escargot/ - MarbleClay
http://www.cbmodelpro.com/ - Non-linear modeller, draw lines on surfaces and move the lines to shape models.
http://www.caligari.com/Products/trueSpace/tS3/resources/default.html - Truespace 3.2, it is an older version of Truespace; but still a good solid modeller. The free download is at the bottom of the resources intro.

Blender (http://www.blender.org) is a lot more than just a modeller. It can model; but it can do a lot of other things too. It isn't the most user friendly app.; but it is not unlearnable.

Friends don't let friends use booleans.