taxi fares

The prices are per trip.

Can you tell me how much your taxi cost? I assume it was from your hotel to the airport?
I'm looking at a trip with Gate 1, and they want to ad an additional $180 for a shared airport shuttle to and from the hotel.

My taxi fare from the airport to my hotel in Sultanahmet was around £21.

Best thing to do is ask your hotel how much a taxi should cost. If the price sounds good, ask if the hotel can arrange that for you. When leaving Beyoglu near Taksim Square for my flight at IST, the taxi driver charged only US$20 ( I tipped him heavily) During a three-week trip in Turkey I found a common charge to be $20 for a one-hour taxi transfer, $40 for two hours etc. whether I was in Istanbul, Cappadocia, Izmir or Antalya— this standard in the pricing seemed to be very common. The minimum wage in Turkey is less than $3 per hour. Turkey’s had years of runaway inflation. Because of the ever-decreasing value of the Turkish lira, taxi drivers were happy to accept U.S. dollars.
The HAVAIST Express Airport Bus for $3.50 ‘travels from IST Airport to Taksim Square, Sultanahmet and 40 more locations in central Istanbul. These are clean, modern buses with AC and upholstered seating. Buses leave from the -2 level under the International terminal where you arrive, “the floor beneath the basement.”
Take the elevator or escalator to the -2 Level.and ask which Bus Line# is going to the district your accommodation is in ( I.e. Taksim Square, Besiktas and Sultanahmet to name 3). Then walk on the sidewalk until you reach the ticket booth of your Bus Line# where you can use credit card to pay for the $3.50 ticket. You won’t need any Turkish lira, so visiting the ATM gets to wait until the next day.

You can take a carry-on aboard the bus with large luggage getting tagged, you get a numbered receipt and the staff stow the heavy luggage safely in the storage compartment.

When I arrive at IST, I take the HAVAIST Airport Shuttle into town. www.hava.ist
Going to the airport is the time to use a taxi that you can easily arrange after you’re in Istanbul.
Highly recommend 1. walking across the GALATA BRIDGE that links the old city to new town on the other shoreline. Pedestrians have their own dedicated bridge level— no cars to worry about.
2. If it’s too hot in the city, cool off and take one of the public ferries from Besiktas Ferry Port to Yenikoy near the Black Sea. The ferry passes some of Istanbul’s largest mansions, that are known as the “Sea Mansions.” Turkey’s original Presidential Palace is one of these. The medieval Ottoman fortress from 1452, the “RUMELI FORTRESS” was built by the Ottomans to control shipping on the Bosporus.

Rick Steves’ book on Istanbul nicely summarizes the points on interest along the ferry routes and at the port neighborhoods.
Have a great trip!