If you search my posts in this thread, you will find some eBay seller recommendations for the RFL 6N3P-Es. The one TVNO mentioned is one of them.
On matching, you can look at it in different ways; I've only found the difference from triode to triode, or tube to tube, to be about 15% max, and usually much closer than that (~0-7%).
With that in mind, and with the intention of matching channel SPLs, you can match by ear (center image), or SPL meter. (You can use a Vali2 to do one tube at a time, one triode per channel.)
Or, you can match by voltage output in your own amp (or Vali2 first), which is simple to do with a V meter, and then confirm by ear. What better circuit to use than the actual amp itself?
I do always listen to the tubes first to identify any noise or sound issues. These tubes have a very high QC level.
And yes, you can find/buy matched pairs.
"It’s just hard wrapping my head around tubes being “good” that inexpensive."
Quality design/construction/performance does not always align with market prices for NOS tubes.
The European and the USA tubes have had a much longer exposure in the western markets, and that establishes price levels, and... let's not forget hype!
IMO, the Reflector 6N3P-E has one of the highest levels of design/construction/performance that I have seen in noval tubes, from any brand or country.
But again, IMHO.
(And remember, all of these small format tubes sold for just a few dollars apiece in their day, regardless of their price today, whether that is $2 or $400!)
Edit: Here is one post, but you can find more...
https://www.head-fi.org/threads/schiit-lyr-tube-rollers.673709/page-903#post-13688879