
Holy mackerel, that alto went for a pile of cash!
That should make you very happy, Andy.

It makes me happy as well. I have a couple of alto Koch recorders in cocobolo and one in black cherry. I paid a bit lower than that for the black cherry one, but it came with an issue of a recorder periodical with an article about Koch, was in absolute in-the-box mint condition and had the original paperwork and accessories. The two cocobolo were in exellent condition as well and I paid less than half that bid for those.
The prices on these have been going up lately. I think it might be a bit inflated so I probably will let it settle down a bit until there's another tenor up. The recent tenor was listed so that only a few people interested would find it. I missed it entirely.
There is a soprano out there with a very high ask right now. As far as real value, these are undervalued. One would have to pay a great deal more to get a better made and playing recorder despite some of the issues pointed out in that book Andy brought up. The latest model Moeck and Mollenhauers might be a little better. I have to wonder about these others because I haven't seen some of them. And the German fingering system ones I have that are Harland inspired are very diverse. One tenor has undercut tone holes and it just plays absolutely fabulously. It's unmarked but definitely a Harlan inspired instrument. The tone is very reedy and it is in Dmajor, looks like sycamore to me. It has an archaic brass articulated key mounted in a raised wooden ring. It's made to look Renaissance, but it's probably from the 1930s.
Tuning on these, if one has a consort by the same maker, is probably not a real issue. The instruments would not have been in equal temperament during the Renaissance or baroque period. The modern idea that this should be the case is one of convenience and utility for the present. If these are played the way they originally were, it is more important that the consort be harmonious when played, not that every note be in perfect equal temperament. So the best way to judge them is to play the same fingerings on a matched consort. I am close to a matched consort of three makers. I still have to get the basses and one tenor.