Buy tubes from Audio Research or not


I need to retube my amp and I'm having trouble deciding whether I should buy my tubes from Audio Research or buy them on the open market. If you have any experience with this I'd appreciate your help.
taters
He's getting the tubes from the actual Importer. They are going to match the tubes for him. Then he will install and bias them. He has retubed ARC gear in the past so I believe he knows what he is doing.
Samhar...what tube tester do you use in your set up? Are there any current suppliers of tube testing equipment or does one have to buy an old used unit?
Samhar...I just saw you are using the Hickok 539b from your System thread. Is the manual sufficient to walk through a complete newbie like myself on how to use the unit and what to look for when testing/measuring tubes? Thx