Need recommendations for inexpensive power cord


I’ve never used after market power cords and am considering buying a couple.  I have some questions:

Considering the astronomical price power cords go for, is there any point getting one or two in a lower price range?
At what price point do power cords start to make a difference in your system?
I have two monoblock NuForce class D 160 watt amps.  Is this where they should go? 
Can someone recommend an inexpensive power cord that can make a difference?

 
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Anything below the Audioquest Thunder should serve you well. Maybe a blizzard or a monsoon power cord. Even an AQ Nrg Z3 would suffice.
What's the shortest power cord you'd recommend for a 20 amp Furman 20 I conditioner? I have a wall outlet right behind it and could literally make the cable 12" and it'll give me room to spare but I read somewhere that you want no less than 3' or a meter?