4500 does sound like a good deal for a EM1 (99-00) Civic Si, but before you jump the gun and buy it, get it checked out by a mechanic, last thing you want to do is buy a car in which the motor/trans etc was abused. also check to see if the car has a clean title or salvaged, this may not seem like a big deal but if you try to sell it later it will affect the resale.