Got a line on NOS tubes

Mullard (MOV - Mullard Osram Valve Co.) and Telefunken are most desirable. Along with Amperex, Brimar, Philips and RTI. Next down the list would be US production: Baldwin, Cunningham, GE, KenRad, National, RCA, Sylvania, Tungsol and Western Electric.

Any of the pre-40's tubes (2A3, 10Y, 24, 27, 31, 45, 46, 47, 50, 56 ...) are worth collecting. They can be used to make some interesting pre and power amps!

Most sought-after: Tungsol 5881's and 6550's. EL34's and 6CA7's. Any 6L6 series. Any 12A*7 series, 5751's and 7025's. Any 6DJ8's and 6922's. Any 6SL7's and 6SN7's. Rectifiers: 5Y3's, 5AU4's, 5AR4's (GZ34), 6CA4's, EZ80's ...

If you're getting a primaluna amp you owe it to yourself to find some Amperex DD getter EL34s. It's the best EL34 I've ever heard, I personally like it more than NOS Genalex KT88s

Find out if he has a tube tester. It would have been necessary in that business.
  
  Before you install any tubes, you'll need to test them for different parameters, such as voltage and leaks. Also, most preamps and amps need to use matching tubes.

As for the tube tester, it may (will probably) need recalibration if it hasn't been used in a long while.

Go to the PrimaLuna website, look at the NOS tubes they sell for their amps and the prices. make a list.

Go to the other major tube dealers in the US and go to their website: Tube Depot, Upscale Audio, Tube World, Brent Jesse Recordings, etc. Do the same thing an make list.

Then cross reference with your first list from PrimaLuna site. Prioritize list, and be able to list the tubes by price, which will help you pick out the best tubes and most profitable tubes...

Yeah, he probably has a nice tube tester or 3 laying around.

But good tube testers are easy to calibrate. Just follow the instructions to make sure the electrical tolerances are accurate.

Tube testers ALSO go for big money these days. There are one or two models, like the HICKOK 539C TUBE TESTERs that go for $1200-$2500 depending on condition. Although these Hickoks are great testers, the high price is due to the hype on audio forums, so this particular model will max your flipping profits. Or I’d be glad to take on off your hands :)

And congrats, BTW, the situation you have come across .... the rest of us can only dream of such a gift!