I have a little different take on speaker values. I believe that speaker preference is
so subjective that cost is rendered insignificant. It's not unimportant, mind you, just not very significant to what you believe sounds good in a loudspeaker. Certainly quality cabinetry, drivers, and even looks can have a bearing on what
most people prefer. What you as an individual prefer is possibly much different, no matter what anyone tells you about speaker
values.
I've auditioned many dozens of speakers from 40 bucks a pair up the the many thousands of dollars per speaker. I've A/B switched speaker listening until my ears got tired. But per my preference for their unique sounds, I almost would rank them randomly with regard to cost.
My pair of L/R mains has an MSRP of $1,000. I have heard no speakers I like better that cost less than $5,000 per pair. And though I like those better, it surely is not 5 times better. Not even 1/4 again better. Yes, diminishing returns is at work, and mightily so. But so is my preference for a certain audio presence.
Here's an old thread that has some interesting philosophical posts about loudspeaker quality vs. cost.
http://forums.audioholics.com/forums/showthread.php?t=22802&highlight=high+upgrade
Happy speaker hunting. IMHO, audition, audition, audition, and don't ask how much it costs unless you find one you simply
must have.