The testing suggested by bill_k would be necessary to sell NOS tubes for big bucks, but I think you're asking for less than that, i.e. to check your used tubes to see if they're still good and reasonably matched.
It would be a nice service and if the dealer is selling tube gear maybe he should offer it. I think the time involved might be why most dealers don't do it, though. As you noted the expense for a couple of testers for preamp and power tubes wouldn't be that much compared to monthly rent and equipment to display.
If you can't talk a local dealer into providing the service, I think a tester would be a good accessory for you with the number of tubes you use and your tube rolling habits.
It would be a nice service and if the dealer is selling tube gear maybe he should offer it. I think the time involved might be why most dealers don't do it, though. As you noted the expense for a couple of testers for preamp and power tubes wouldn't be that much compared to monthly rent and equipment to display.
If you can't talk a local dealer into providing the service, I think a tester would be a good accessory for you with the number of tubes you use and your tube rolling habits.