I've got at least one book titled price economics. Basically that's a huge area in economics. There are both micro and macro contributions to price. It's also the one communicative factor between suppliers and demanders.

Price theory. Microeconomics… which is largely how a single actor makes a decision, whether to buy something or where to set a price, and how that leads to market equilibria when many people do that in some utility-maximizing manner.

Also, does this include the psychological effect of price ? selling at 0$ doesn't mean people will grab it, they might assume it's crap.

Thanks nonetheless to both you.

I think a question like that would fall under the umbrella of "consumer behavior".

Behavioral economics.