Typically, my cost to overhaul an automatic will vary with the transmission, but in general, a complete overhaul kit usually costs me in the vicinity of $300. Some are more, most are less. Adding in the cost of a rebuilt converter at about another $300 and I am up to $600 average plus oil. Hard parts are sometimes another factor, BUT I can usually buy a jumkyard trans (as-is and pulled) for about $80. Even so, a NEW gearset runs in the $300-400 range for most units, and drums average about $75 each.
Overall, I can properly overhaul the average automatic for about $750 for a first class job.
I do know all about the skill required to handle a stick shift. I drove big trucks for 21 years in a combination of OTR and local peddle. In a big truck, I would not give 2 cents for an automatic. In a 4-wheeler or 6-wheeler, the opposite.
Regardless: Automatics are smoother. That is simply a fact of life whether you agree or not. Never had one stall on takeoff. Never had one miss a gear or grind.