Do you feel Nordost cables are worth it's asking price?Absolutely not. I don't even find them worth their used prices. Of course many Nordost owners would disagree. Too thin and sterile sounding for my ears. I've heard enough to know that system synergy, personal tastes and such. Couple Nordost cables with warm gear and perhaps they will work better.
What's the proportionate amount one should spent on cables?
Only you can determine the answer to that question. Everyone has their own personal limits. Some folks spend less than 1% on cables while others spend 80% or more of their audio budget on cables/cords.
All will tell you that their approach works best.
Personally, I find cables to be effective part of the audio chain, and spend more than I used to years ago. That said, I have reached the point of saturation too, where cable costs rose to over 50% of the system cost.
I found this to be overkill, and have since backed off a bit. Today, I would say that I am at around 35% of system cost on cables/cords/conditioners.
I'm sure that many will tell you that this is still way too much, others may say it's not enough.
Who cares what others say? You pay yer money, you makes yer choices.
Cheers,
John