You can make your own inexpensive Compost Tumbler by drilling a plastic 55-gallon Barrel full of holes to allow air circulation. Fill it only about 75% full to allow the contents to move about. Then put the lid on securely and roll it on the ground. Roll the Barrel slowly to allow the contents to "tumble".
Try to get a Barrel that contained food products. If it contained chemicals or pesticides, scrub it to remove all residue. Then drill 1/2" holes about every 3" apart all over the sides of the Barrel. This is going to be a lot of holes and it will be time consuming, but balance the time involved against the cost of a commercial Tumbler.
An arrow on the Barrel will allow you to stop rolling at a point opposite where you started rolling. Give it about 5 or 10 revolutions once a week. Reverse the Barrel end-for-end when changing direction, to prevent tumbling the contents back to where they started. The Barrel should always be rolling in the direction of the arrow.
If the Compost does not get warm enough, paint the Barrel black and keep it in the sunshine. Even with the best compost recipe, it is sometimes difficult to generate enough heat in a small "heap". See the Compost topic for a Compost Recipe and watering instructions.