I got a couple jumps to train my first rabbit with. I didn't get very far, though, as I got him a companion and have been working on more basic training like not chewing carpet, using stairs, logic boards, etc.
You can get decent jumps for $20-30. It's a great item to have around to work on with your rabbits and get them some exercise and training. I got one jump from Ebay, and one from the BunnyApproved site. (Is linking to external sites against the TOS here?)