It may not be a wise idea to sell the Birdy - the unfortunate truth is while these are quality bikes with matching prices, the second hand market for folding bikes is a niche-within-a-niche, so there might not be much interest in paying a fair price. I have seen Birdys go for medium prices (bit above 50%) but 75% is rare. Most often the Birdys when these do occur on ebay here, are listed with a buy-it-now price, with maybe takers. There is much interest, but not much interest in paying fair price. I would not list my own unless absolutely forced to.

See for example this one #270514063449, fair price I would think, but no bids. I'll have to see if it goes at $1500.