I just purchased eight of the old EL34 Mullards on EBAY for $200.00,. My current wholesale price list from New Sensor Company shows the Tesla E34 L @ $8.90 each dealer cost.
This makes a total investment difference of only $128.80 for amps requiring sixteen EL 34 outputs. This small difference in price between ordinary tubes the best ever EL34 is the bargain of the century. Obviously everyone must decide where to invest their limited audio budget, but the old magic tubes are often more gain in performance than the same investment in wire, isolation, and equipment upgrades.