My technique has been to check which shops use procut lathes, and then call them up to see if they can do the alignment. Theory is, the procut lathe isn't cheap, and if a shop has invested into one, they've likely also invested into the better alignment racks already. It's also good to get to know the people at local service shops, because using them frequently and being friendly leads to them shaving off little costs here and there (like I pay 80$ for tire mount/balance regardless of my tire size and 105$ for alignment regardless of time it takes them to dial in my exact spec).
I do have a shop I use regular, and get mounts and balances free because I send them business. The problem is my car can't get on their alignment rack. They recommended the other 3 places I tried, and they all had the same rack.