Where to buy decent 845 and 211 tubes?

Let’s start saying most vintage tubes from eBay are junk.... "oh we cannot test this, but this looks like new and should work" with definition of "work" meaning there is filament continuity. or the tubes "used to work a few years ago before going to storage".

Short of paying USD $2000+ for a pair of vintage RCA or United Electrics, what modern 845 and 211 tubes are worth buying. What’s your experience with their sound and longevity?

I will not buy 211 / 845 tubes that cost more than my Viva Solista, much like I would never buy a TV shelf that cost more than the TV itself.  :-)

Most eBay sellers of vintage tubes are honest! I have never had any problems with my purchases! 
If you can't afford vintage 211's or 845's then you will have to take your chances with current production cheap Ch*nese! I wouldn't!
I just retubed my Cary 805 amp with 845T, Genalex Gold Lion PX-300B, and Tung-SOL 6SL7. All current production and they provide a satisfying sound. The 845T replaced an 845W.
What amp?   The bulk of current 845/211 production is from Shuguang or PSVane/Acme.  They make some very good products.  

Elrog I hear makes good tubes.  I have never heard them.  I am thinking about starting to carry them.  

Finally, KR produces a non-traditional 845 & 211.  The filament current on the KRs is 1.0 amps vs. 3.5 amps.  If your amp can handle them, they are pretty fantastic, but are not inexpensive.  Art Audio amps accept them without modification due to our auto bias but a lot of amps need a resistor added.