I use a compost tumbler because I have a small urban yard and someone gave me the tumbler for free. I would not recommend buying one. I think composting works much better when it directly touches the soil, so organisms can come in and out, water can drain, etc. The "tumbling" supposedly helps you to turn the pile more easily, but it's a joke. When you turn the (full) tumbler, everything inside sticks together in one big lump and just flops over onto the other side. There is very little mixing going on.
In my case, the tumbler is necessary because it can sit on concrete without making a mess, and it completely hides any evidence of composting from my neighbors. Otherwise, keep looking.
