HDMI 2.1 is so new that there aren't good testing methods for this. In reality, it is supposed to mean that the cable will support up to 42.6 Gbit per second data bandwidth. Many manufacturers will "say" that it's HDMI 2.1 certified, but who can tell?
The best I can give you are a couple of cables that are actually tested and certified for HDMI 2.0. This means that the cable has been tested to support up to 18 GBit per second, which is enough for full bandwidth 4K video. If you google for "DPL Labs" you will get the company and you can drill down into their site to get the list of certified cables.
Out of that entire list, the only two I would recommend that come close to your budget is a USED Wire World Ultraviolet 7 HDMI or a USED Nordost Blue Heaven HDMI. It's hard to say which one of these would be better. The Nordost uses better copper. However, the Wire World Ultraviolet has bigger 24awg conductors so there will be more "oomph" in the audio and better color saturation, but it could have a noiser digital signal which can come across with video noise or bright audio.
If you look closely, that cro-treated Neotech is almost exactly the same as the Nordost Blue Heaven. It's just that the Neotech has never been tested for "certification" on the newer hdmi standards. I bet that these two cables would test almost equal to eachother!
The best I can give you are a couple of cables that are actually tested and certified for HDMI 2.0. This means that the cable has been tested to support up to 18 GBit per second, which is enough for full bandwidth 4K video. If you google for "DPL Labs" you will get the company and you can drill down into their site to get the list of certified cables.
Out of that entire list, the only two I would recommend that come close to your budget is a USED Wire World Ultraviolet 7 HDMI or a USED Nordost Blue Heaven HDMI. It's hard to say which one of these would be better. The Nordost uses better copper. However, the Wire World Ultraviolet has bigger 24awg conductors so there will be more "oomph" in the audio and better color saturation, but it could have a noiser digital signal which can come across with video noise or bright audio.
If you look closely, that cro-treated Neotech is almost exactly the same as the Nordost Blue Heaven. It's just that the Neotech has never been tested for "certification" on the newer hdmi standards. I bet that these two cables would test almost equal to eachother!