knockdown          
adjective uk/ˈnɒk.daʊn/ us/ˈnɑːk.daʊn/
 (价格)降幅大的
(of the price of something) reduced by a lot
  They quickly realised why the property was available at a knockdown price.
 The game is now selling for a knockdown £6 in B&M stores. 这款游戏目前在B&M商店以6英镑的折扣价出售。 
  低价的;价格降幅大的
cheap, or reduced in price by a lot
  They are selling the knockdown fuel for just over 50p a litre.
 Hundreds of bargain hunters descended on the market, drawn by the promise of knockdown art. 数百名淘便宜货的人抱着买到廉价艺术品的希望涌入市场。 
 - More examples
 - He obtained the flats at a knockdown rate.
 - The Danish international would be available at a knockdown £4 million.
 - The apartment is available for a knockdown rent .
 - A small group of oligarchs grew rich from the knockdown privatisation of state assets.