I personally think the tramp boards are a waste of money. Just go to your local hardware supply store (lowes, home depot, etc.) or a package/shipping supply store and pick up a piece of spongy foam. It's shipping foam for a rectangle shaped box. You can get them thick or thin, depending on what you like. I'm not talking about Styrofoam, but the cushy type foam, so it won't be brittle and crumble. I think I got mine in a box that was shipped to me, but really don't remember.
The piece I use is almost identifcal to the size of my board. Cut two holes in the place you want your sudo-bindings to go and slip your feet in. This keeps your feet stationary so you can't cheat on your spins, but doesn't rip up your trampoline. The foam will actually be resting around your ankles, but works really great.
I find the tramp boards or anything you use to keep your feet stationary, much more realistic and harder to do spins and just about anything. I definitely don't use it enough.