When I first bought my land....you could barely set wheels on the land due to the stumps. I had a heckuva time getting from one end of my land to the other on a 4Wheeler. I rented a few different grinders.....namely 25HP Vermeer, and 25HP Rayco self propelled stump grinders.
The Rayco was hands-down the best grinder. I think I paid $150 for an 8 Hour day of grinding(either model) - plus I had to re-fuel it before bringing it back. Sometimes the grinders would be in excellent condition.....and I got allot of work done in a day. Other times the teeth were dull or the belts were fried or some such issue. I ground out about 600 stumps IIRC with the rental grinders. As many as 200 per day.
After a couple of bad grinder events (nothing accomplished)......I decided to upgrade my tractor and buy my own stump grinder. I had bigger dreams of land clearing then.....as compared to when I started out. (I believe I have now ground out over 2200 stumps....but it could be more.....I've lost track.).
My point is that the rental grinders are not too expensive to operate....and you can get lots of work done if you get a good machine.
I would NOT do very many stumps with one of those handle-bar grinders. They will beat you up and spit you out. ;)