Killer vintage 70's, 80's reel to reel to add to my setup.

If you want to throw $20,000 at it: https://sonorusaudio.com/atr10

This deck is based on the Revox PR99 chassis. It uses a combination of original parts and new parts. As an alternative, you could just get the cleanest PR99 you can find and send it to Sonorus or to Soren Wittrup for refurbishing. You'd very likely come in under $10,000 in that case.

Regarding your choice of machines, you must first decide what you need.  If you are going to collect high end audiophile tapes, you will need 15 ips speed, 10.5" reel size capability, and 2-track playback.  If you have, or will be collecting 4-track tapes, you need 4-track playback capability.  If you are going to record your own tapes, you need to decide whether you want 4 track recording capability or just 2 track capability.  If you are going for 4 track playback, you should decide if the ease of reverse playing is something desirable.

I like the Technics line of machines.  The 1500 is a 2 track machine that also has a 4-track playback only head; just flip a switch and it will play back 4-track tapes.  It operates at three speeds, including 15 ips.  The 1506 is a 4-track machine (meaning it can do 2 track record and playback and 4-track record and playback).  The 1700 is an auto-reverse 4 track machine.   These can be had well within your budget, although mint and never used machines cost considerably more.  At your new budget, you should be able to get a fully reconditioned machine that has been lightly used.  Plenty of machines were made, and there are plenty of parts available.

The Revox PR99 mentioned above is also a nice machine that has a lot of parts availability.  

Thank you @larryi for the wealth of knowledge and excellent suggestions. I've learned a lot from this thread and all that have contributed!

I'm coming around to the looks of the Studer A-820. Damn solid machine.