ARC VS110 tubes

I will be changing my tubes on my VS110 in the near future. Unit is 1.5 years old and bought new from an ARC reseller. Should I buy factory tubes from my ARC dealer or the same model from some other tube vendor (such as TheTubeStore.com). I was told that factory tubes are perfectly balanced for my amp... not so with after market vendors. BTW I have no interest in tube rolling at this time.

I noticed that when buying from ARC tubes are more than twice the price than online vendors, why is that so?

Thanks for your reply