top dollar

(chiefly US, idiomatic) The maximum amount of money that an item, service, or worker is worth; a very high price.

Example: 1947, "Aces Up," Time, 8 Sep.,
  Within six months, Goodie was back in radio, earning just about the top dollar for a writer ($3,000 weekly) as Danny Kaye's chief scripter.
2006, "Many ways to say cheese," Toronto Star, 6 Dec., p. F2,
  Consumers are willing to pay top dollar for distinctive, rare, traditional cheeses.