I just got an offer of 10% off, for $100, from the seller (was in my Watchlist - some sellers will send out discounts if you sit on the Watchlist for a while).
RE: waiting for e5-2699 v4 price drops... Don't hold your breath. Every "top tier chip" will always demand a premium on eBay over one or two steps down. It will always be like 150% or 200% the price of just dropping one or two models down. Case in point:
E5-2699 V4 (22C/44T) right now around $450-ish (non-China)?
E5-2698 V4 (20C/40T @ 2.1) ~$250
E5-2697 V4 (18C/36T @2.1) ~$200
RE: ES/QS versions of these chips... I am now banning any and all ES/QS chips from my life, never again. ES/QS chips were the only way I could afford V1/V2/V3/V4 over the years because back in 2014, there was no way I was going to pay $2000 for a CPU where I could China an ES version for $400.
To this day, I have 7 or 8 ES chips that are... Just not right. Odd random full system freeze/lockups, occasional memory errors, etc. The amount of trouble these ES chips have caused me, thinking, "It can't be the chips. has to be the motherboard. the bios. ok, i'll try beta bios. ok, has to be lsi controllers. nope, has to be the chassis. missing a ground... etc etc" years of frustration and too much money, never suspecting the ES chips.
Then I got a deal on eBay for the exact models of a couple of the ES chips in a dual system I was using, but in retail form. 100% stability! i mean, I haven't rebooted the server in almost 2 years. I have even put in my old big memory kit I thought was unstable, and it's just fine now! I am even taxing the machine far harder now, and even added another 14 drives. Zero issues.
IMO, stay away from ES/QS chips. Especially for how cheap you can get some of these retail chips.