2wd 1/10 is more expensive to stay competitive. Yeah you can run rtr but if you want to be competitive, stay away from tire hungry/setup sensitive 2wd cars. 1/10 4wd scts and wheelers are expensive as well wheelers cos they break easy and scts cos you need the best $$$ batteries and bodies tear up fast.
So cheaper to run is definately 1/8 initial cost is high but later on you just pay for tires which is good.