self copyright, send registered letter to yourself and dont open it. it's sealed and stamped by a govt entity, presentable as evidence in a courtroom if needed. apply for patent gets the patent pending status mentioned by someone here previously, costs little and offers some protection for a while, produce immediately!
yes China or elsewhere aint gonna care about a US patent, so dont bother, get in and out, move on to another idea the same way. nafta-gatt handed China the contents of OUR patent offices anyway to leave invetors no recourse for compensation was really cute, so keep it in mind anytime 'they' want something.