Professional video stabilisers are prohibitively expensive. You won't get $10,000 worth of stabilisation out of a $US14 DIY model, but you will get radically smoother video for a tiny fraction of the price.
How does the DIY model provide smooth video? Instead of the complex arrangement of balancing mechanisms, resistance bands, and springs, the DIY stabiliser relies on a simpler system. Your arms and a counter weight at the bottom of the stabiliser work together to minimise the movement. Camera shake is radically reduced when the weight of the camera is offset by a equal or slightly heavier weight at the bottom. Sound about right for your needs? You'll need some pipe, a disc weight, some hand tools and a power drill to put this one together.
For photos and a step by step build guide, check out the PDF below. If you need to stabilise video in a car, check out how to make a dashboard stabilizer out of a sponge. $14 Video Stabilizer [Make]