Hi John
There is a bit about changers in archives,to add to my previous comments the Boxer LX changer which we use can do up to 24" wheels is semi auto with assister arm, which is a must,does all of our needs and never let us down.
Main thing to look for is a strong remove/fitting arm that does not give under heavy load as can damage alloys.
As for balancer we have had a Cemb C31 for many years and has programmes for alloys/stick on weights,not a fancy machine but does all we need.
Be careful of tyre suppliers if you want to stock,as prices can vary a lot as with valves/weights etc.
Good luck
Tony