How do you determine how much to spend on speakers

I think the ratio between the costs of the components changes depending on the budget for the entire system. For example, if I were going to build an audio system with $1000 I would spend about $400 on speakers, $400 on amplification and the rest on a disc player.
If I had a 5K budget, I would spend about 3K to 3.5K on speakers, 1K to 1.5K on amplification and the rest on a disc player.
It seems to me that as the budget increases a larger percentage of the total cost should go toward the speakers.

Older thread - if I was going after a 5K system, I'd start collecting "keepers" to build upon later. Oppo's earlier mentioned at 1K now have 32-bit DAC's and rated Class A, plus Oppo has great support for newbees. Next, I'd determine whether I wanted near field, mid field or far field "sound". Multiple crossover's and multiple drivers can sound a bit congested at near field. That being said, most near field set-up's are two-way speakers with one crossover. At mid and far field, bigger drivers and often multiple drivers/crossovers become more common because the sound smoothes out at distance.

If you know a multichannel active speaker line sound that you like, say the Paradigm Active Series, this may be a savings over separate speakers, amps and more cables. I'd consider buying the two active smaller rear's first, and use them initially as your front mains as a mid field 2-channel system. Later, I'd add a matching musical sub and the larger front main's and center.

For non-active speaker's, I'd also consider the Oppo, the earlier recommendation of a adequately powered integrated amp or "regular amps fed directly by the Oppo (use the Opps volume control)", and add the speakers. This approach builds a surround system off the original purchases. Good topic for new buyer's.

I listen to all speakers I can that purport to be "state of the art" or "reference level". I ignore price as much as I can. They I pick my favorites and decide if I want to spend that much money.

So far my favorites are at $75k, $50k, and $35k. That's right.... winners over the field of near $200k speakers, thankfully. I can be nearly as satisfied with the $35k speakers as the $75k speakers. It's important to be honest with yourself and to avoid "dreaming" about owning a speaker just because it's out of your price range, or because some reviewer raved it. Everyone wants what they can't have, that is part of the human condition.

I'd rather listen to my favorite speakers with a $1k amp, a $400 cd player, and a $800 used preamp than splitting the money up more evenly. And I do have those pieces at those market values, along with state of the art pieces to compare them to, so what I'm saying is based on experience.

If you could afford those favorites you pick, without materially changing your standard of living, but your wife won't let you buy them, my only advice is to try to pick your audio equipment more carefully than you picked your wife!

Main thing is to make sure speakers are not undersized relative to the room. Larger more expensive speakers typically with larger and/or multiple drivers are needed for good full range sound in larger rooms.

IF you do not care much about extended and balanced bass levels, you can get by with something smaller.

There are even some larger monitor style speakers out there that may be up to the task, but you will often pay a premium for those and rightfully so.

There are many schools of thoughts on this subject but I would spend twice the amont on [2] speakers that I would spend on amplification.
Same principle applies to source components, again I would spend twice the amount on [2] speakers.
With a $5,000 budget that roughly works out to:
Amplifier: $1,200
CD or Turntable: $1,200
Speakers [2] $2,400
with $200 left for decent cables.
BTW, you can get a damned good system with a $5,000 budget if you do your research, shop around and yes, haggle. Always be prepared to walk away...