How do you determine how much to spend on speakers

Much depends upon the speakers you choose in terms of the needed amplification. As a Maggie owner (3.6s) I need more current and watts than someone who prefers horns.

That said, I have McIntosh 501s driving them and a matching McIntosh tube preamp. I bought the electronics used and the speakers new so my balance is about 2 : 1 in terms of preamp, amp and source versus speaker cost. I am not counting the music server I just added as that is an "extra" that not everyone would chose to own.

make up a budget, then only spend $1000 more than you budgeted on the speakers.

that's a plan

If your goal is the best possible sound today, splurge on components and then add reasonable capable speakers. Don't cap a mediocre system off with great speakers unless you are committed to upgrading those components down the road. Great speakers just let you hear more of the source.

What ever the wife says.

Alas it is my bank-account,not I that 'makes' the decision.
Otherwise I would directly order the biggest from Nuddel.
Regards,