This has been an extremely tough challenge and perhaps the only coin that I'm missing is a rather pricey Chinese-Soviet crown coin. For now, I'm very happy with this
http://www.gxseries.com/numis/china/china_province.htmSome highlights in this collection are here:
Yunnan-Sichuan

Chinese-Soviet (Jiangxi Soviet)

Qingdao (German colony at one stage)

Guizhou antimony coin - rather unusual material

Here's one thing I would say - I am very lucky that I started this coin collection at the start of the mad Chinese price hike and some of these coins have easily tripled by now. Some are even unobtainable no matter how much I want to fork out for instance the antimony coin, which pretty much appears on auction markets once in a blue moon.
Not a set that I can create a duplicate anytime or attempt another similar set...