On my recent trip in March 2018, I thought I'd save money and book my taxi in advance to the airport from New Town, Edinburgh. Online airport taxi bookings are listed for various taxis and mine was for A1 Taxis. I had to leave for the airport at 6 am. I paid £27.50 IN ADVANCE. The taxi never arrived. As I had checked out I didn't have internet and the phone number for my reservation went to an office open only 9-5. I had my hotel call me a taxi and it only cost me £17.50. At the airport I was able to read a message that my reservation was cancelled by the vendor around 3:30 am. I did get a full refund. However, be aware that these online booked taxis are very likely more expensive and not more economical as they advertise, especially at the times there is not traffic, and in my case the service was completely unreliable.
where were you staying, £27.50 sounds reasonable from the city centre and £17.50 a little low.
sorry you were let down by A1.
I use local buses including late night buses to get to the airport most of the time unless someone gives me a lift.
I was up by Queen St. Gardens. Yes you are right that £27.50 is an "average" fare which is why I booked it. I should have been clearer in my post that (1) lower fares may prevail at hours with low traffic and thus a better deal than a reserved taxi, and (2) calling a taxi at the time you want to travel is an alternative (that worked for me); (3) web reservations may mean there is no way to contact the company outside of 9-5 and (4) the reservation doesn't guarantee a ride because if your driver cancels it appears that there is no backup.
I always use public transport when I arrive (I love the tram!). But going home I had excess baggage, and there was snow, so the walk at 5:30 am would be tricky.
Last September, upon arrival in Edinburgh, I just got in line at the airport and grabbed a cab to my hotel (on Salisbury Road, in Newington, not far from Holyrood Park). The cost was £26. For the return trip, my hotel called a cab to go to the airport and it cost £29. Maybe more expensive because of the distance?