There is a cheap alternative to the Rogue Dogsled online made by Xtraining. I paid $250.00 including shipping. It's made in China, but it is built like a tank and gets the job done. I used it exclusively on grass outdoors. If you have good size clumps of say, crab grass or dips it would hang up every now and then. You definitely can't use as much weight, but it doesn't matter, because it will still kick your ass. Expect to be pushing low as well, because of the increased resistance of grassy surfaces. The rise of the angled cut of the base is about 3 inches, so if you don't have a huge amount of dips and clumps you should be good to go. Also, you won't be able to use the plastic skis on grass either. Fringesports also makes an almost exact Dogsled as. Xtraining.