What is considered a good silencer in the USA where they are legal but strictly controlled and heavily taxed ($200 for each) and where they are lightly controlled and not taxed are literally continents apart.
Americans pay $150 (22lr) to $3500 (50 bmg) for each silencer (plus tax) as well as waiting 3-6 months for approval to make or buy. This means they want state of the art and a very durable product. If I was able to buy one for less than $100, I would only care about size, weight and suppression. After it was worn out from excessive heat or filled with gunk, I would just throw it away and get another one.
I understand that some 22lr silencers are made partly of delrin. If this is the case, hopefully it has some sort of blast baffle made of metal up front. Even aluminum will erode in a few hundreds rounds if you shoot fast.
If someone is trying to sell a plastic silencer, I would limit it to use on a bolt action rifle.