gazump

/ɡəˈzʌmp/
verb
  1. To raise the price of a property after already agreeing to sell it to someone, usually to accept a higher offer from another buyer.
    • They were afraid the landlord would gazump them after they had already paid the deposit.
    • The seller tried to gazump us by asking for $20,000 more just before we signed the contract.
    • In a hot housing market, some sellers try to gazump buyers even after a verbal agreement.
Synonyms