I cannot see myself ever paying more than $500/ £500 on an amp or CD player. I have done in the past but I'm no longer convinced it was money well spent.
On the other hand I used to think that $5k would be my limit for speakers but I'm no longer sure about that either.
All of those I've seen under £5k seem to have one form of serious compromise or another.
I'm now beginning to think that $10k would be my limit for a pair of minimum compromise loudspeakers.
From very early on in my audio journey I grew to dislike small, minuscule upgrades. All of that time and trouble were just not worth it.
Besides, I never got much long term satisfaction from those kinds of upgrades. It was often a case of some plusses but also some minuses which kind of ruined it a little.
A true upgrade should simply be sonically better in every way.