The M6 and M5 haven’t shipped tet, just preorder stage so they’ll come down once the nee one’s land. A good proxy is the M2 mini dropping to ~$250 after the M4 hit.

Eg. https://uptradeit.com/buy-used-refurbished-mac-mini-2024-sil... ($269)

I’m hopeful for even lower than $300 prices just because there’s a lot of homelab people spending a lot on these and the M5 ultra really does make the M4 not worth using for that use case. So there should be a flood shortly hopefully.