As with most used vehicle purchases, the engine is always a dicey point. Sellers often say the engine is fine, when in fact the engine is worn out.
Most RTR's need a replacement servo. So a replacement is a good deal. Ask for the brand and model of the new servo.
Also, is shipping included? No need to lowball the seller. Online purchases are always a crapshoot, unless you know and trust the seller. $135 isn't bad. Just keep your fingers crossed.