Cavelettis are raised poles, usually about 6 in-1 foot high. Some people use them for jumping exercises, some people use them like you would ground poles, but the lift makes for a little more difficult work.
We've bought several jumps from JumpPVC. I think I get some mail from JumpUSA or something too.
Make sure they understand that leaving the arena or going back to the barn does NOT mean their work is over. This might mean riding in the ring for 5 min, walking down to the barn, immediately return to the ring, go back to the barn, etc etc. sometimes i'll even hop off and put them in a cross tie in the barn and then hop back on after 5 min or so. On some horses i'll spend a day just trotting away from the barn (we have a really long dirt drive away from the barn) and walking back towards it. Maybe ride in the parking lot a bit. When i'm finished I always hop off and loosen the girth, THAT is the signal that the ride is over. Usually i'll get off in the ring or somewhere and then hand walk back to the barn. The key is to switch things up and keep them working everywhere you go.