Carb parts and side covers are readily available. $150 is cheap, if your going to buy it
check the gas tank for rust (both inside and check for rot at the bottom of the exterior of tank) pull the magneto cover off and see if the engine turns, check for crank bearing noise. Check the stator/electronics for rust and or water damage. Spin the rims and check to see if there true. Inspect chrome parts/wheels for rust. Check to see if the engine number matches the frame stamp. Check mileage on the speedo. Note condition of the wiring harness, lights etc switches controls. Check forks for function and straightness.