Tube vendor recommendations?

Another vote for Jim McShane. Great person, very knowledgeable and has always given helpful advice, even to the point of tracking down the technical specs for my amp to make sure the bias point was appropriate.

Andy of Vintage Tube Services

I've used Brendan at Tubeworld for a long time, but have done business with Brent Jesse, and he's good. I like the Tubemonger too- he gets some offbeat tubes - never used flying lead type converted to conventional pin and socket type. Andy I've heard of, and Jim is a new one for me, who I'll check out. 

RAM Labs for me too. Roger Modjeski has a vast knowledge of tube design, construction, and performance parameters, as well as amplifier circuits. He often provides tubes to other amp designers such as Mike Sanders (Quicksilver Audio) and Ralph Karsten (Atma-Sphere).