For $20, you won't get much. Maybe a table top tripod or a very cheap tripod.
Monopods are good for sports shooting because they are fast. You don't have the set-up and take down time of a tripod. A monopod will prevent camera shake in the vertical plane but not in the horizontal...although it's better than hand holding.
Typically I see monopods used with big heavy lenses. 300mm, 400mm, 600mm etc.
I think the cheapest one I've seen was $50 or $60 CDN.
You might be able to make something...all you need is the right size of screw and something to mount it on...hockey stick, tube, pipe, baseball bat etc.