Oh, those kind of things. We've got a lot of those in the Philippines, and most of them operate whole day. There's even a whole city for that! But I haven't got into one of those, never mind at nighttime, because crime rate in the Philippines is very high, and I'm not gonna take chances. But yes, most items sold on those places are really cheap, even exotic things like precious gems or something. Some are even fake, but I don't know what those are made of... In my school there was a joke that anything made in China was fake, but now I have thought that China-made things are a lot cheaper than original ones but the same quality are better.
I learned that pasar malams are the almost the same like flea markets (called tiangge in Filipino), maybe because of the kind of things they sell. Where they got these things they're selling is what I'm anxious of, and why they sell them at really low prices. Pretty confusing, no?