i'm not chinese, however if I was, your racial statement might be offensive.
It's clear you don't do any internation sourcing of parts.
You can get cheap junk or as high quality as you can pay for, out of china.
Some of the most advanced non govt restricted electronics are coming out of chinese manufacturing plants right now.
It's the smae with tools. You can buy pure junk if you spec and pay for pure junk. You can buy quality if you spec and pay a lil more for quality.
Look for tools at larger chain stores, they will usually have return and warranty policies as good as any big name tool company... Also with a large chain, if multiples of 'type x' part start getting returned in droves.. they can go to the manufacturer to resolve the issue.
You can get inexpensive CH air metering valves at TSC and some walmarts. they DO work.. and you can verify they DO work if you have a set of test gauges. A set of reference gauges belongs in any shop doing repairs with any frequency. One must also keep 'scope' in perspective. The OP wants a low budget paint setup for some auction paint jobs. He doesn't need a new 1300$ upright air comp, a binks paint gun and a ton of other 500-2500$ equipment i could list. He wast an inexpensive gun to blow some inexpensive paint out on some stuff to make it look shiney instead of dull. You don't use a sledge hammer to drive a tack... keeping his 500$ budget in perspective, it's helpfull to provide advice and options within that budget, even if it is mentioned they are not production quality materials or tools, and if they are production quality tools, they may not have the lifespan of a more expensive brand name tool..e tc.
Speaking of tools again. have you noticed many 'american' branded tools are comming over hear by boat. sears/craftsman is but one example.
I hope there were no chinese people reading the forum thet you offended by your remarks...