How do you determine how much to spend on speakers

I spent about 45% on my speakers. Then again, its a surround system and they're more speakers to go round. The issue of balance is a very important point because you certainly don't want any more power than is needed for the speakers, nor do you want insufficient power going to your speakers. I had B&W N804 powered by McIntosh MC205 and was more amplifier than the speakers needed, so I upgraded to 803s (the best I can afford). Still the power indicator needles don't move very far.

The fellow that bought my N804 was going to power them with NAD 50 watts per channel, and I told him "gahhhhh nonononononoo" Can you get at least 100 oer side? He was moving to Korea and shipping the speakers back. Apparently its costs less than buying them there.

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.