In Barranquilla Taxi-Cabs don't have a metter, so it is possible for the driver to charge you more than usual if they think you don't know the rates.
Also, Uber platform will allow you to report if you have any inconveniences with the service the money if you where charged more you will get the overcharge back. It happened to me once.
If you want a more affordable option, Transmetro is great. Remember that you can transfer from one bus to another with the same passage if you take the next bus before an hour has passed.
Good luck in Barranquilla and enjoy.
"Quien lo vive es quien lo goza"