1
general::
Phrase(s): bid something up
to raise the price of something at an auction by offering higher and higher prices; to increase the value of something, such as shares of stock, by offering a higher price for it each time it comes up for sale. • Who is bidding the price up on that painting? • Someone bid up the price on each piece at auction and then backed off.
McGrawhill's American Idioms And Phrasal Verbs
2
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Raise a price by raising one's offer, as in We were hoping to get an Oriental rug cheaply, but the dealer kept bidding us up. This phrase is used in business and commerce, particularly at auctions. [Mid-1800s]
American Heritage Idioms