gazump
raise the price of something after agreeing on a lower price
wordnet.princeton.edu/perl/webwn

gazump verb (gazumped, gazumping) colloq said of someone selling a property: to raise the price that has already been verbally agreed with (a prospective buyer), usually because someone else has offered a higher price. gazumper noun. gazumping noun.
ETYMOLOGY: 1970s in this sense; 1920s as gazoomph, meaning 'swindle': from Yiddish gezumph to swindle.

gazump /zmp/ verb [vn] [usually passive] (BrE) when sb who has made an offer to pay a particular price for a house and who has had this offer accepted is gazumped, their offer is no longer accepted by the person selling the house, because sb else has made a higher offer
gazumping /zmp/ noun [U] —compare gazunder

The first explanation fits better with the definition in these dictionaries. But the Oxford Dictionary of English also has the second explanation, like the one with the typo:

gazump - make a higher offer on a house than (someone whose offer has been accepted by the seller) and thus succeed in acquiring the property

So I think both explanations are needed, perhaps with a little more explanation in the first.

gazump
/gzump/

• verb Brit. informal deprive (someone whose offer to purchase a house has already been accepted) from proceeding with the purchase by offering or accepting a higher figure.

— DERIVATIVES gazumper noun.

— ORIGIN originally in the sense ‘swindle’: from Yiddish, ‘overcharge’.

http://www.askoxford.com/concise_oed/gazump?v...

Ferguson [...] is wary of losing potential transfer targets to Chelsea. Arjen Robben, Mikel John Obi, Michael Ballack and Michael Essien have all turned down moves to Old Trafford because they could earn more at Stamford Bridge [= Chelsea] and Ferguson believes there is a definite trend of Chelsea trying to gazump them in the transfer market.

http://football.guardian.co.uk/News_Story/0,,...

Wolves are likely to want in the region of £4m for Lescott but Everton's valuation is believed to be nearer £3m, with any disagreement over the fee offering Portsmouth a chance to gazump their Premiership rivals.

http://football.guardian.co.uk/News_Story/0,,...

Alternatively, several of Europe's other leading clubs may attempt to gazump United in the five months before an official announcement can be made. Although Ballack is described as having made up his mind, he has not signed a contract or made any legal agreements that cannot be broken.

http://football.guardian.co.uk/News_Story/0,1...

This, too, pleased luxury retailers as they see it as a way to gazump the all-powerful high street.

"You can get a slouchy woman's tunic at different price points. But if you want a great pair of trousers or a dress with delicate pleating you're going to have to spend a little more," said Massenet. Well, the customer can't always win.

http://www.guardian.co.uk/uk_news/story/0,,20...

The roots of the problem lie back in 1994, before the internet reared its egalitarian head as a mass communications medium. Then, the IOC signed a $4bn deal with the American broadcaster NBC for exclusive TV coverage of the Olympics from 1998 to 2008. NBC wants to show "live" Olympics at prime time in the US, to maximise advertising revenue. But the time difference between Sydney and the US means NBC is going to delay all its coverage by half a day. The network fears the net could gazump it by offering video to the US audience before NBC gets round to its "live" package.

LAWYERS will this week quiz New York-based investors about their rumoured plans to gazump the Barclay brothers’ takeover of the Telegraph newspapers.

http://business.timesonline.co.uk/tol/busines...

Nobody loves a deal like Diller, and it would be rash to rule out IAC attempting to gazump its deadly rival.

http://business.timesonline.co.uk/tol/busines...

[Die timesonline.co.uk-Links sind leider nicht mehr aktiv, sie finden sich nur über eine Google-Suche nach gazump site:timesonline.co.uk)

Ich bin so frei und grabe diesen Faden vom letzten Jahr noch einmal aus (immerhin ist er genau ein Jahr alt, lustiger Zufall).

Ich habe "to gazump" im Guardian inzwischen schon öfter gelesen, wenn es nicht um Häuser, sondern um andere Waren (gerne um Fußballspieler) ging. Einige Beispiele finden sich oben. Auch der Oxford-Eintrag ist allgemeiner gefasst. Da die meisten anderen Wörterbucheinträge aber tatsächlich auf Immobilien beschränkt sind, würden mich Meinungen von natives interessieren, ob eine Aufnahme einer allgemeineren Bedeutung sinnvoll wäre.