Bicicyle_man, in fairness, I have seen "museum quality" TFK 803S's go for as much as $1400 a pair on eBay (before the financial meltdown!) They ARE rare, and if one is a collector (and has no intention of using them - which blows my mind ;-) I suppose . . . . . .
But if you were to do a little research as I did, purely out of curiosity (I wondered what a $1400 pair of 12AX7's must sound like?) you would probably discover as i did that the concensus was "nothing special"!
The only time I [almost] got badly burned buying NOS tubes (the seller took them back ;-) was when I paid a premium for some truly NEW NOS tubes and one was a complete dud. But nobody knew because no one had ever tried to use them! Oh yeah, the seller had tested and measured them, but not actually placed them in service in a component. From then on, I only buy ANOS (almost new old stock) tubes with at least a few hours on them. There's nothing like a 'track record' when it comes to tubes!