GAZUMP
gazump
(verb) raise the price of something after agreeing on a lower price
overcharge, soak, surcharge, gazump, fleece, plume, pluck, rob, hook
(verb) rip off; ask an unreasonable price
Source: WordNet® 3.1
Etymology 1
Verb
gazump (third-person singular simple present gazumps, present participle gazumping, simple past and past participle gazumped)
(British) To swindle; to extort.
(British, Australia, real estate) To raise the selling price of something (especially property) after previously agreeing to a lower one.
(British, Australia, real estate) To buy a property by bidding more than the price of an existing, accepted offer.
(British, Australia) To trump or preempt; to reap the benefit underhandedly from a situation that someone else has worked to create.
Noun
gazump (plural gazumps)
(British, Australia, real estate) The act of gazumping.
Etymology 2
Noun
gazump (plural gazumps)
(US, slang, dated) An automobile.
A politician who takes bribes.
Source: Wiktionary