If you are a citizen of a big city, you can get a permission to visit HK (a big city's citizenship is damn hard to get, estimated 100,000USD for one BEIJING citizenship in average cost of efforts. Citizenship, called HUKOU, is vitally important in China). If you are a citizen of a smaller place, you are allowed to go HK by joining a tour group, where the tour manager is supposely held responsible if you flee to a hidden corner in HK not coming back (in reality many tour group organizes one-memeber-groups for a fee to workaround the regulation). Hence you can organize a HK Bitcion tour, everybody go shopping in HK, shop for goods and coins. perfectly legal AFAIK.
Sorry man but China is seriously fucked up country.
Damn, that shit about permissions of leaving country remind me of dark period of my childhood when the country I was born in was communist Yugoslavia. What a dipshit communism is..
FYI, the HK border restriction is imposed by HK government to prevent influx of illegal workers.
Chinese, as far as i know can freely leave their country as long as they have Visa to the foreign country.