Good things don't come cheap, cheap things often aren't good quality. 前面很直接的翻译，这两个也表示差不多同样的意思 - "if it sounds too good to be true, it probably is" & "you get what you pay for"

Tom's answer isn't bad. Another way to translate it is: Quality isn't cheap. You can't expect quality at a low price. Another phrase with a somewhat similar meaning is: "You get what you pay for." but that is translated as 『一分钱一分货』

「好貨不便宜，便宜沒好貨」 How about this: "Good stuff costs, and cheap stuff sucks." ?? :) --- Good weekend. / 祝　週末愉快。 / 좋은 주말를.

Goods are not cheap. You get what you paid for.

No good cheap goods, good not cheap goods