i would go used over a clone any day. the key is find something local, have a good look over it, if your buying it rtr then have it demoed to you. you will have to replace worn things, but you will be better off in the long run. as said, you will end up with the same money into a clone, but it'll be broken far more)
$700 is peanuts in large scale. i got into large scale with a $150 rolling chassis with servos, i had $800 into it once it hit the road, and $1500 into it before i could call it reliable. if i were you id do some research on parts cost for 1/5 scales. check out what consumables cost (tires, wheels, gears, dogbones, diff outputs, bearings, etc) and ask yourself "can i afford this?" if hesitate to say yes, then walk away from 1/5 scale. you don't want an ill maintained 1/5 scale. these things can weight 30+ lbs and go 45mph, if something happens and it gets loose, it can be deadly