Like Entwisi posted earlier, it's always worth asking for something off for cash. Retailers put the cost of people paying by cards into the price. For American Express retailers pay 10%, so it's a useful bargaining tool.
When I bought my house, even though property was selling fast at the time, I asked for five grand off because I was paying cash. I got it for the price I wanted, but the ding bat I bought it off never got the carrier bag of notes he at first envisaged.
