its not that they would have to source them, more its just the order of doing things to insure you dont order something that wont fit.
I dont know a machine shop yet who will say for certain that it will polish up, and order bearings based on that.
they will polish it and then order you bearings.
so if you ordering the bearings yourself even cheap from america then you should do the same, order after the crank is sorted.
what you could do if the lead in time for bearings from america is long, take the crank and get it sorted first, and order your bearings.
before you worry about pistons or rebore.
spread the cost over time.
Phil