Michael,
I hear what you are saying, I just don't think that setting a price is the way to musical enjoyment long term. It's the way the industry survives, by encouraging endless upgrades but I don't think you can put a value on sheer musical enjoyment. I like the Linn Classik, it makes music and boogies. So on a budget I'd happily live with one.
Above that, well there is very little on the market that makes me want to rush home from work to put some new music on, maybe even a different genre such as bluegrass or baroque. And any upgrade from the Classik would have to do that to justify the increase in cost, whether that be £5 or £5,000.
So what I a getting at is that any upgrade from basic hifi should show an immediate emotional connection that speaks to the heart and forces your wallet to open. Anything else will soon sound the same as your previous kit (once the novelty of the soundstage depth and treble extension has worn off), and you will start looking around for the next upgrade that will ultimately fail to satisfy.
And all because the purchase is made with the head and not the heart.