There is a real shortage of American made sportbikes. The only ones I can think of are Buell, Roehr (not in productin yet) Fischer
Buell has been around for a while now, they even have some entries in some of the popular roadracing venues around the world. (Off-hand I can't think of any that have really been successful and won a championship while racing against some of the other more popular sportbikes.) They offer a line of about a dozen different models ranging in price from $5,000.00 to $12,000.00 and displacements of 30 to 73 ci.
Exotic styling with American technology brings Fischer to the high performance table with absolutely beautiful style and performace for under $8,000.00. They've sold out the production runs, but are taking orders for 2007 delivery. The MRX 650 boasts 77 horsepower and 52 foot lbs of torque on it's high revving liquid cooled 90° V-Twin.
Another new company, Roehr, is not yet in production with their new sport bike. In fact, it's not even finished prototyping it yet. It will run the Harley Davidson Revolution engine. Aside from that, not much is known about this bike, including the price. But what we do know is the wheelbase: 56 inches. The Rake/Trail: 24deg./ 97mm. Dry weight: 435lbs. Seat height: 31.5 inches. They produced the RV500 and the RV1000, both race machines with limited quantities being built. I'm not sure if Roehr will ever get into affordable production. Instead, I think they will focus on race bikes.