I like trampolines. I haven't used mine much yet I just got it last month. I bought mine from a sproting store around here. It's a brand called InMotion, 36" and folding (although it does look that the folding is not worth the effort). It seems stiffer than I thought it would be but it is really fun! I youtubed some trampoline exercises, but really it looks like most of the cardio you can do otherwise is just put with it, and I'm told you work a lot of areas bouncing around.
If anyone is interested I think I paid like 40something plus shipping on their site. I'd have to dig up the name of the place. I should have just gone over and picked it up though. I called Wal-Mart and K-Mart and they both proceeded to tell me that they do not sell mini-trampolines, just big ones!!

You know how mad I was to see one at Wal-Mart with a little computer thingy and everything!! Argh! (I wanted to go get one not get one off the site at the time)
Either way, mine is only rated for 250lbs. I'm close to it and it still seems quite strong. It's the spring kind, but the springs are covered. I wanted a bit higher rating. They rate between 150-350 as far as I've seen, and some places don't tell you the ratings!!
Also they come in bigger sizes... I've seen 36, 38, 40, 42, and I think 48. Prices vary... something like 40-150 or so.