I have got a 2010 MGM with less than 30 races on it. I have set a 2 cycle engine on it just to have fun but if I have the right offer I might let it go. Always finished on top every race in the clone class with this chassis.
Trouble is...... determining what is "used" and what is "flexed out". I have always been fond of Invaders and Coyotes. Coyote parts are more available. What dealers provide the best trackside support in your area? Budget? Lots to consider. I had to go back and re-read your post when you stated road course. To most, road course means tracks commonly 2+ miles in length. Then, that would open up other options as well.
Call Greg at Margay,
For the price and all the extras that I received from them you can't go wrong buying a used kart from them. The best part is the information they supplied me. They are just a phone call away or a email.
Hope this helps.
At this time of year, you can good a good price on any of the above chassis in used condition. I am sure you can get a 08-10 roller for $750 ish. You just need to find a Tach, wheels, tires and body work. I know SteveK51's stuff is always in good shape.
If you can find Birel, go for it! On any of the sprint chassis, you will need to make sure the inside drive chain will clear the tube behind the seat. Some chassis are made for outside drive 2 cycle only.
If you plan on racing 4 cycle engines.. Buy a kart designed for 4 cycle engines. Don't buy a kart that was built for 2 cycle and then worry about how to make it adapt to your 4 cycle platform. Determin what type of seat you want to use. Layback/oval style or the situp 2 cycle style. Some chassis, it is a struggle to get a layback seat in them some chassis you cannot put the situp style seat in easily. Many are running 4 cycle karts with situp type seats with their Animal, LO-206 or Clone motors on them.
Shop for a purpose built 4 cycle chassis, Margay, Coyote, MGM, Bandit, Razor to name a few, they all build 4 cycle chassis. Get the model and serial number off the kart and contact the manufacture or an authorized dealer to find out about the kart. I am sure where ever you live you can find one in your area and price range.