High value, giant killer speakers?

I would vote for two speakers.
1. Tekton Design Ulfberht. Amazingly dynamic and realistic full range sound.
2. Triton Reference. Powerful and refined.

Both sell for about $9,000.

I find that the Dutch and Dutch punch well above their weight, in particular due to their acoustic design.

I wouldn't describe them as being necessarily cheap, but when you consider that they have all of the electronics already on board (amplification, dacs, dsp, room eq, and eventually roon), the value proposition starts to become very strong.

In general dipoles play nicer with your room than box speakers, hence Maggies, and my current home built Fostex 103/Eminence Alpha 15s.

Quad ESL 57.  For me the 63s and their derivatives throw too much treble and midrange energy into all but the largest rooms.

Vandersteens - all of them.  I honestly prefer the 2s to the 3s, even though the 3s are more accurate, and the 2s with a pair of the subs over the 5s, for the same reason.

Siegfried Linkwitz was a giant; it would take the price of a new car to best his Orion speaker system. Behold the dominating sound stage, my audio brothers!

I have auditioned many speakers over the years from $3k-$300k and IMHO I was blown away when I heard a little known speaker in the USA that was reasonably priced retail $6k that crushes many speakers more than 5x,10x their price. The speaker is made by Amphion in Finland. The price performance is oof the charts. I spent approximately two years auditioning speakers and amps before investing. When allocating a significant  amount of money for a high end system, after all that testing, I bought the Amphion Argon 7L on the spot. They are quite efficient at 91db. When paired with a good amp you will be delighted. I actively continue to audition speakers and amps and thus far have not found a speaker that outperforms at this price range. Worth a listen if you can find a dealer.