dao ye. dao means to buy in one place and sell in another (an example of how Chinese has far more verbs than English). The literal meaning of ye is grandpa but it is humorously used to praise someone. The dao ye are people who buy little stuff, such as clothes, in Southern China, where it’s made, and sell it in Beijing. Probably on the sidewalk.
chao fang tuan. Chao means stir-fry (fast cooking), fang means houses or apartments, and tuan means group (of people). The chao fang tuan are those who speculate in real estate. They buy a house or apartment and sell it quickly. “Everyone in China hates the chao fang tuan,” said my friend.
Although mainly applied to the buying and reselling of financial instruments, the verb you are looking for is ‘arbitrage’.
The house people are called “flippers” in the U.S. Not super popular these days although most of them got badly burned in the end.