der Mondpreis — Moon price. A price set at random and far too high. In retail jargon it is also an invented “recommended price,” printed only so that the real price looks like a bargain.
das Lockvogelangebot — Decoy-bird offer. A Lockvogel was a captive bird used to lure other birds. The offer draws the customer in for something else. Competition law bans several forms of it.
der Apothekenpreis — Pharmacy price. In colloquial use, a price that is out of proportion to the product.
die Abzocke — Rip-off. The word comes from zocken, to gamble.
der Nepp — Overcharging. Das ist der reinste Nepp! That is a pure rip-off!