market value???

A fiarly high amount as I recall. I think there is a demand coming from Asia as well at the moment.
The amount it is worth is what someone will pay for it jn a free market.
A big auction site is not a bad place to watch and see what they go for (as Peter said). At that point you'll know what price range to ask for, or set a reserve at. Don't make the mistake of seeing a high asking price and thinking that it sells for that, watch for completed sales, asking doesn't mean selling.

I try not to attach too much emotion to inaminate (sp?) objects. I would never be able to sell anything. I have a hard time as it is. I don't hoard most things but things, but I like like old tubes I just can't seem to get enough of them. I have in fact given some away rather than solling them.
Best of all is a true win win trade if possible. I do have to unload a few things though.
I have bought far too many project vintage amps, mostly by Sherwood of Chicago. My father had a Sherwood 5000S which used 7868 power tubes. It makes silly claims like- 80 watts- on the face plate. Yah- perhaps 80 watts both channels driven into clipping or beyond, really can't imagine it but... they seem to drive the vintage 50s JBL speakers pretty well. So yes I bought a bunch of Sherwood amps for no good reason. especially after I had one restored and a friend gave me a refurbished tuner that matched. That one is fun but I ended up with 2-3 others I never use.
I should probably sell off most of the stuff I don't use, slowly, a few at a time. I alone could prolly manipulate the market by flooding it with certain items. The tubes always have a lot of competition and I aint no dealer, so I'll get bottom dollar, except for the rarest and most desirable which I'll want to keep for myself.
As for the TT in question I noted that it wasn't the model I thought it was at first. Now I don't think, at this point, even if fixed up by a pro, will get much. I am sorry about my first prognostication.