When you ask "good purchase under $20" does that infer the max you want to or are willing to spend is $19? 'Good purchase' is a liquid term, ie what is good to you may not look so good to someone else.
But, if you are willing to spend $20 for a faulty set, maybe with some patience you can find something better for a little more money. You probably saw this on
ebay and in no way am I advising you to buy it, but it's an example of possibly superior material for not much more than $20.
https://www.ebay.com/itm/SCOTT-C1-C...cectupt=true