Apliu has a few stores that sell some brands. A LOT of Nitecore, and prices vary wildly on some items. I got my EC2 for 50 bucks, street number 208. Next door they were selling it for 65. For the most part, like 90% of the items, the prices will be similar to what you find online whether they are shipping from Hong Kong, or the States. Every single store had the i2 charger going for ~$16 (and I looked in probably 10 or so stores). There are a few stores near that store (both left and right of it), and across the street that will look like lightbulb/lamp stores, or just hardware stores. You have to go inside and they have flashlights there. Mainly Fenix, Olight, Zebralight, Jetbeam, Nitecore (MT1A was ~35, EC2 was $50-65, TM11 was $200), Klarus (XT2C ~$65USD), Niteye, Xtar (SP2 ~$24) brands. One store sold a bunch of ****fire and what looked like every Tank007 model that exists.
Down a block is where SolarForce is located. You can buy parts, hosts, batteries, lights. It looks like a camera supply store (bags, tripods, lightboxes), but in the display window it's SolarForce lights, and only SolarForce lights.
There are other stores as well, which I haven't been to, but may be going to check out soon. One is in Wan Chai (apparently selling Crelant, FourSevens, Thrunite, Nitecore, Fenix, Olight, JetBeam, Sunwayman) , and one is in Fortress Hill (selling Nitecore, Xtar, and NexTorch).
Again the prices are VERY similar to what you find online unless you are looking for ____fire brands, and no name brands that are sold in the little shanty shops in the middle of the street. The stores are behind the shanty shops, and while some have flashlights displayed in the window or near the front, many have their flashlight section inside, or randomly scattered inside (either with empty display boxes, or zip tied to the wall). That means you have to walk into a lot of stores and look. Some stores will look like lighting stores, and some will look like hardware stores.
I also picked up the cheapest DMM in the store which was $4, and again, you can almost find that price in the States during a sale/online.
As for batteries, again a lot of Nitecore batteries, and I'm not an expert in batteries, but they had red and purple 18650s that claimed to be Panasonic, or Sanyo, but I have no idea if they are legit or not. The Nitecore 2600mah 18650s were $10, which I didn't buy. They also had 16340s in OEM solid colors, but I'm even less of an expert at that. Eneloops, AA/AAA 4 packs were $10, akalines are so cheap that it would make any serious environmentalist fall into a spiral of madness.