I have looked high and low for one of these on the 'pre-owned' market. If you end up scoring - Id gladly pay you to run a bundle of my EL34s through it just to get a ballpark for pairing!
I bought both the preamp and power tube maxi-matcher testers new about 6 years ago. One of the best investments I’ve made. I know exact what goes into every amp I own and I can replicate what I like.
Good luck on the hunt.
Yea, I looked a long time too. . I did see about 2 per year show up 'used' but the prices weren't THAT great, so I held out, and that was dumb . Ha. . Good luck