This steady cam only needs a few non-printed parts, the rest can be printed. Z rotation is enabled by a 608 ball bearing, while the other two axes are just running on M4 screws.   
The design works great - of course, a "pendulum type" steady cam like this one has some drawbacks, but it's still good enough for some really nice action footage!  
After designing this, I found one which is also very simple and cheap and additionally has a very nice design: http://www.thingiverse.com/thing:84142. Maybe I should have searched first ;-)  I really liked MaximFilm's idea of the handles for the threaded rod, so I decided to adopt it and also add one above and below the gimbal.  
Anyway, this one is even cheaper. I paid 1 Euro for a 1m M8 rod and about 3 Euros for almost a kilogram of nuts and washers at our local hardware discounter. The most expensive part is the bearing - if you have to buy it. I took mine from an old pair of rollerblades. So, together with approx. 20 meters of PLA, total cost is much less than 10 Euros.  

This thing is also on Thingiverse: http://www.thingiverse.com/thing:283925