If Quicksilver as well as many other brands are made in China, I don't get the differences anymore.
China is a country, not a company. There are thousands of companies in China with the capabilities of making these parts. These companies are different, have different business models, and therefore different quality control standards. Just because something is made in China these days doesn't mean it's bad, but that doesn't mean all Chinese made goods are equivalent. If Quicksilver is going to put their brand on a Chinese part, you better bet they have vetted the company making the part, and that they are still inspecting parts that come from the company to ensure they meet Quicksilver's quality standards.
So....live everyone else is saying, you get what you pay for. You saved a hundred or two hundred dollars on a bellows kit. If it fails in 3 years and you have to replace it, will future you be happy with past you for saving that seemingly small amount of money?