The kuble trades quite favorably with it until it gets a gun. The price difference is only 10mp before that so it shouldn't be beating its ass too hard.
Well, tbfh the upgrade makes it very potent. Can it still carry a squad after it is upgunned? Even if it traded 50-50 with kubel after the upgrade it would be a much better vehicle. With crew and many useful abilities. Its mg is better than kubels' at fighting infantry. So to make it a better design a price increase of 50 would probably make it somehow at least "pay" for all the goodies. It wouldn't be enough but you just can't make such a vehicle too expensive.