Power Cables diminishing returns

I'm thinking of upgrading my PCs, but am wondering what the sweat spot is as far as price. The price point after which, you see diminishing returns. for example a $1000 is certainly not twice as good as a $500 cable.
I wanted to re-visit this important subject. It would appear that OP has not responded for some time? Anyone know about his buying decision?
Second, in 2013 & 2014 I have had the good fortune of listening to some outstanding PC(s). Here are my strong suggestions; 1st place is no doubt the Stage III Concepts offered by Brian @ Aaudio imports. 2nd place goes to Silent Source offered by Frank / based in Dallas TX. 3rd place is a tie w/ Signal Cable and the newest Wireworld Electra 7.

All of these PC are outstanding, to say the very least. Each is at a different price-point and requires careful consideration based upon the 10-20% cost of overall system value. Happy listening!
Its impossible to but a money amount on on the equipment, when raising ,percentages.What happens if you buy used equipment that say was originally sold for 5,000 and now sells for 500 .Stop playing the jealous neighbor, enjoy what you have .But be careful of BS prices.
Completely agree with you. I upgraded from stock to all Frey 2 over the past year and it made a significant difference in my system. 

I also use Frey2 or TYR2 (speaker cable) for my interconnects especially the XLR. 
Thrilled with what it has produced. 

I have found the Wywire Platinum to be the sweet spot for me.  If i can get them used all the better.