Shoulder rigs help you stabilise your camera -- in this case your DSLR -- while maintaining mobility. We've featured these before, including an inexpensive PVC option, but this one is the simplest and cheapest approach.
You can assemble a shoulder mount by following the instructions in the video above. It offers thick grips, simple assembly and easy camera mounting. If you're on an extreme budget, building one of these will offer a greater amount of control for the cost of a decent dinner.
DSLR DIY PVC Shoulder Rig [DIY Photography]