The difference a power cord can make in your system is very large, particularly on the power amp. Power cords like interconnects and speaker wire can be considered in a couple different ways: quality and effect in your system. My meaning here is that greater quality usually means a greater impact on the sound quality… but it does not mean the effect is positive to your system / to your ear.
Generally you must try some different ones. I recommend the lending library at the cable company or local dealer. I would try used cords. Include Cardas (a bit warmer) and AudioQuest storm series. Typically you get used at 50%… putting you in a much higher quality category. The AudioQuest Storm series has taken the community by (sorry) storm… they are such a big jump forward in sound quality. Also, I recommend DHLabs… they make really great products in your price range.
My experience with the lower end Shunyata has not been good… as in, they just don’t seem to be much of an improvement… at least in the systems I have tried them in.
On my system, I spent a year trying different cords until I found the AudioQuest Hurricane, not in your price range. But the effect was so profound and did exactly what I wanted… complete transparency, with a dead quiet background. Adding power cords to my components had a much smaller but important impact. I used Transparent on those and they did exactly what I needed them to do. And these all replaced Audio Research’s very heavy duty stock 20amp cords… the difference was really important and very positive.