Cornering the Market
When you buy up a specific item, and inflate demand artificially. Sometimes people do this with scratchcards or codestones, items that are cheap, but bought frequently. They buy all of the ones up in their Grouping. Then they hope people won't search more than once in the wiz, and just buy from their shop. Sometimes it works, sometimes you get left holding a lot of stuff. If it's a risk you're willing to take, go for it.
Here is an example of orn codestones. The first is priced normally.
The second shop is priced normally.
The third is ginakay trying to corner the orn codestone market in her group. She has bought up a ton of all the cheaper ones, and is trying to unload them fast. She wants to sell them before people in her group start pricing them at a lower rate, like 4400. If they do, she'll probably have to buy it and add to her stash, to make it 28 she's trying to sell (she has 27 right now, presumably all the people's codestones that she bought up, priced between the market price and 4,691).
Every time someone puts it lower in her group, she has to buy it, or else it'll take a few minutes before a random buyer buys it, in the mean time, more people have put up cheap orn codestones in her group, and after a while, no one will ever want hers, cause it's expensive, and not at the top of the list. It could work if a lot of people aren't thinking and you can make out an extra 200-300 points per codestone here.
You could also get stuck holding codestones that are overpriced. Supposedly she bought the cheap ones, at 4400, but also the expensive ones, from 4500-4691. She overpaid, hoping someone else will overpay.
If you see this happening in your grouping, you might want to take advantage of it, by putting your stuff for a higher price, and either someone will buy it thinking it's pretty cheap, or the person cornering the market will buy it trying to make themselves look the cheapest. If neither happens after a while, just go back and put it at a normal price.
If you're ambitious about it, you could get a few friends and buy up ALL of a certain item in EVERY group that's cheap, mark up the price and try to unload it before others start selling it for cheaper or market price. Lots of risk, but lots of profit if you can pull it off.