A guy around here bought the IB B18 package, and it performes real nice. He's had no problems with the thing, and has been beating on it pretty hard for a coupla months. I can't vouch for anything personaly, but they seem like a legit place, the only problem is the cost. If you were real mechanically inclined, I think it'd be more fun to do the same package that you're thinking about buying and building it yourself.
Ian