like said depends on budget..
as for motor depends on how big/small is your track also if you want to run mod/stock..
im assuming its a clay track? get clay tires.. i like to run soft/super soft due to its winter and track stays more wet/slick ect and dont dry out as much compare to summer..
servos i use savox never had issues and great price..
as for buggy.. 22 2.0 is nice comes with pretty much all the upgrades and can go mid motor as the rango can too.. the 4.2 is great buggy also but no mid motor from factory. you have to buy a conversion kit if you want to run mid set up.
batteries theres lot to pick from just make sure its approved by your track if they check for roar.