The offers are based on two factors: 1) the going resell value of the given card to establish the dollar value and 2) to get the bitcoin offer, an aggregate of several bitcoin exchanges at the time an offer is made. A user has five minutes to accept a bitcoin or cash offer, otherwise, the offers expire. They can re-add the card to get an updated offer, if desired.
CardKaChing.com || Sell Your Gift Cards for Bitcoin or Dollars