Where to buy JUST a tube mic with no power supply?

Huh. How does that happen?

 My understanding is a lot of them are cross compatible. Maybe that's bad info though?

Aside from appropriate voltage, the pinouts might be different meaning: 1. you send power to a part of the mic that isn't expecting it (=smoke), or 2. you don't get signal back from the mic, where the PSU is expecting it (=silent).

I recommend you ask for a pinout mapping for the PSU, then get a pinout mapping for any mic you plan to use with the PSU.

Never assume, even with same pin out, that (often custom) power supplies are compatible / swappable. In many cases voltages are not the same but even if they are, the allowable current draw (based on power rating, etc.) might not be enough, noise/ripple sub-optimal... Need to carefully do your homework beforehand to be sure.

 Is mic building a service you offer?

5 years ago maybe... but work, life, family. 

I’ve considered it, but after the issues first time around I was a bit reluctant.

 Thanks for the suggestion! It just seems like a waste to have a brand new power supply with no mic. Plus it does make the mic less expensive  -every once in awhile Ive seen a good deal on a tube mic pop up with no supply, but its unpredictable

Jacob
Being the cheap ? Ok thrifty AE I am here is what I would do; contact Ben and maybe a couple of other builders and find out what mics could be used with the PSU with little to no modification, then sit tight and see if any pop up. Or see if someone like SVART will put it on a bench tell you the pin out & the specs then if you see a mic you might be interested in without a PSU get the PSU pin out & specs from the manufacturer and at least make informed decisions.

This is the reply from you that I expected! Good on ya

  So. Waited a full month to post - Beesneez/Ben reached out on this thread - March 16 I contacted him as he suggested, he made a very generous offer for a discounted mic. I confirmed I was interested, asked when it could ship. March 26 (ten days from initial contact), he says it could ship that week. I emailed him to confirm where to send payment. Nothing. Messaged here again to confirm payment - still nothing. 

 So, after a full month of trying to take him up on an unsolicited offer he proposed, I think Im giving up on trying Beesneez again. This kind of aligns with my first experience with Beesneez.

My advice to Beesneez would be: Hire someone- even part time!- to literally answer emails in a timely manner and capture orders and support inquiries in an efficient way. I know I am definitely not the only one who has had communication issues. This is probably a factor in why when one of their mics needs a warranty repair (as my first one did) people get frustrated and they complain more publicly about the issue trying to be heard/seen.