At the rate charged per hour most times is cheaper to replace than rebuild.If a trans job takes 40 hrs at 70$ per hr.Your out 3000 in labor only.Plus parts.Now you also have warrenty to consider.I used to rebuild engines for automotive use.1 warrenty will eat 4 engines,Yes you will get a warrenty if you do it long enough.I know its cheaoer to sorce a lift youself.I see a lot more replace with good used rather than repair.If you can buy a running lift for 5000 and a repair is 4500.Then repair might be an option.
you have to just weigh your options.