I try to avoid plugging other websites, as it is a bit impolite.

However, I found vendors or service providers in HK by posting a relevant question on the asiaxpat.com website, on the 'tech and gadget talk' forum. People in HK will tell you where they go. They seem to be a very tech savvy bunch in the HK membership.

Taobao does have ratings and the number of transactions over time. You can also filter by total cost (item + shipping) which gets round the old problem of 1000 rmb ipad and 10000 shipping.

There is also a part of Taobao called TMall, I am not sure but think it is approved traders. Other will be able to better advise.

Mozzies
The local Hualushui with added repellant I have found very effective. It is the one in the glass bottle with green liquid. It can be found for sale everywhere. We live in a high mozzy area next to the lake and a pond. This stuff works.

You might find it a bit hot for pantyhose right now. Hold ups will be cooler, and easier for the squatty potty. But again, perhaps a reason to practice squatting, and think about directional flow.
My wife always complains about the high price and low quality of hosiery in China. She usually stocks up in M&S when we go to Shanghai or HK.

I think Amazon US will deliver to China. But Amazon EU may not.
Not used Amazon.cn.

Regard Cannon, Sony, etc. There are official sellers, but there are also fake stores, that have all the decor of an official store. Gome stores may be a good starting point.

I always buy electronics, cameras, watches, stuff like this in HK. Providing you buy it from one of the longer term vendors, not the street market, it should be genuine. HK is about 4 decades ahead of PRC when it comes to consumer protection.
Prices in HK are much better, there are no real bargains or discounts in PRC. I can get a good cheap Casio for about 300 HKD, whereas I have been asked much more for unbranded sinowatch, of unknown quality. Computers are cheaper and higher specs are available, also lower specs can be bought at knockdown price.

I found vendors in HK, for stuff I wanted, by posting a 'where can I buy?' type question on the asiaxpat.com website, on the 'tech and gadget talk' forum. People in HK will tell you where they go, and even give you directions from the nearest metro/subway station.