with a little research you can do it your self.not getting out all the old oil and not evacuating properly will cause low performance on the hottest of days and up and down temps. if you dont get the bad stuff out it takes up room in the systemthat could be used to remove heat.
I am surprised that anybody can still buy r134a Ive seen that restriction coming,I agree its mostly to do with politics and big money.
you think thats a pain in just a few years 2010/2015 they will phase out r22,thats the stuff in most of your home and business ac equipment.but dont worry for a price they have a legal replacement,but it wont work in the present equipment so you can replace that too.At 5-8 bucks a can it would not be a bad idea to buy some r134a and put it away for later.