We own a pair of Wisper 705 step through bikes, they are approx 6 years old, both in as new condition, one is on its original battery, the others had a new battery approx 18 months back after the original failed. We are going to sell them and buy a couple of fold up bikes. Have no real idea what price to advertise them at, i was hoping for at least £500 each. What do you think would be a fair price. Any advice appreciated