My experience in China is that everyone is caught up in this fervor to be progressive. Anything that hints at nostalgia and the old days are usually less popular. As with pens and ink. Although I say this, it does not mean that there is not a small group of collectors of pens, and also those appreciative of what they call pen calligraphy that has brought renewed attention to fountain pens and ink.
Unfortunately in China, there are no brick and mortar stores to speak of that would sell pens, paper and ink, the likes you see either in Taiwan, Singapore or Japan. That's because they are just not as popular and don't command the economic power like a good ole electronic mart or an Apple store. The best you could do are stores that sell individual brands, such as Lamy, and Parker, which are quite easy to find, as well as Montblanc and ST Dupont, that are quite prevalent as well. Unfortunately I DON'T recommend purchasing from these stores as their prices are just ridiculously high, especially Lamy and Parker. Often double of what you'd pay.
Now it does not mean that there are no unique products to be had. Most of the best stuff is unfortunately only available on Taobao, China's equivalent of Ebay/ Amazon. There are very unique pen makers, such as Tang pens, and the now legendary Pen BBS inks. Unfortunately its really not open to people outside of China as it requires payment through Union Pay and Chinese bank accounts. So not great news.
If you're interested in Hero or new brands like Kaco, you might be lucky if you were to browse at what is the equivalent of book/ stationery street. The street is filled with shop after shop that sell chinese calligraphy supplies and cheap books of classics. You can find meagre selections of Chinese made pens. Unfortunately their prices are usually twice what you'd pay on Taobao.
Sorry not the best news.