We've made XC jumps from old tires! If you check with a tire supply place they usually will give you the old ones they pull from cars for free. We put the rightside up (like they are on a car) and then put one stack of sideways ones at each end to keep them in place. You might want to put a ground pole in front and behind the line of tires to keep them from rolling if your horse hits them. Cheap and easy!