For many months still searching for the big one ! (tube dac)
It seem that the tendancy is Korean, Chineese, Taiwanese fairly unknown plug and play cheap dac that promise you the sonic paradise before you die ....
Hagtech Chime DAC!! Made in USA!
I mean high end dac not DIY.....
Lector DigiCode tube Dac?????
Accustic Arts Dac II.
Just to clarify i am talking about DAC in the 5K to 20 K that usualy appear on the used market at 1/2 price...
Perhaps we are still off season (summer time)
not tube but what i would get if i was in the market:

theta generation VIII 2

my ears have not heard better
I doubt if you would consider it, but the Exemplar XD-1 DAC in its most recent form is flatout unbelievable. I have not heard anything that approaches it regardless of price, and it cost $2500.
I thought you were looking for highend DAC not just high price DAC. The Chime from Hagtech is highend without the high price tag. You can order factory built, you don't have to DIY. Take a look at some of the reviews. Good Luck!
Stay tuned - It appears that Alex Peychev of APL HiFi will be coming out with 2 standalone DAC versions based upon his highly regarded NWO 4.0 player, 1 of which supposedly will be pretty identical to what's in the Esoteric based 4.0, minus the transport.

I currently have a Denon 3910 that he modified for me last December with 4 32-bit 1st generation AKM Dac chips, Class A tubed output stage, digital input, etc. Using my UX-1Pi as a transport, it sounds better than the Esoteric's DACs plus my G-0rb rubidium clock most of the time (except on SACDs).

His new DACs supposedly are much better than the modded Denon, but I won't know until I receive mine, hopefully within a week or so. I've been waiting over 1 1/2 years for this piece to be done, and it has apparently gone though several different iterations to get to its present form, now using lots of second generation AKM 32-bit DAC chips. I will hopefully know more shortly.
If you can find one used the Lessloss DAC 2004 MkII. New they are EURO$2995.
Sorry Lessloss is not tubed.
Jadis JS1 MkIII and Zanden 5000 MkIV Signature are both in the $15-20k range new (I believe) but whether you will find any of those used at 1/2 remains an entirely other question. Also, second Accustic Arts Tube-DAC II SE as one that would have to be on your shortlist.

Echoing Racamuti's thoughts in respect of price vs. quality, I would lend Yamamoto's brand new YDA-1B tube dac an ear (appr. $3k in Japan, haven't seen a price in the US or Europe yet). Here's the - sort of "poetic" as usual - description on Yamamoto's website