Jing county (泾县 Jīng xiàn) in Anhui province has been making Chinese paper for over a thousand years, since the Tang dynasty, so a taobao search with 泾县 turns up a lot. The biggest Chinese paper factory in China is in Jing county, and their most well known brand is Red Star (红星牌 hóng xīng pái), which is what friends recommend I start with.
Stamps and seals
I have a Chinese stamp that I use on my paintings alongside my signature, the problem is that the red ink fades really quickly, almost disappearing within a year. To get decent quality red stamp ink the best place (I’ve been told by those who know) is the Xiling Seal Company (西泠印社 Xī líng yìn shè), their official website is here, and their taobao shop here.