With the admin fee, we found in mail order products that most people really didn't look at the total price, for us we were sometimes a little bit more expensive but our delivery was cheaper and we always included batteries but customers were always blinkered by the main price. Both of those prices seem good to me but lease rates on 500's and fiesta are that low it's pointless buying almost new. If you could afford the hit I would reduce the prices to £4999 and £5999 that way if someone searches on autotrader with a £5000 or £6000 budget then your car will appear in the listings. You could try similar with the mileage.