The main telco provider in Colombia is Claro which is also available in many other Latin American countries. Movistar and Tigo are also available though they have relatively poor network coverage compared to Claro.
Where to Buy Sim Cards In Colombia.
I always arrive at terminal 1 of El Dorado international airport, I've never seen sim card booths in the arrival halls but you can buy sim cards at any of the gift shops and mini-marts around the airport.
Claro's prepaid sim card prepago facil costs 5000 cop ($1) though expect to buy it at a higher price at the airport.
I buy my sim cards and top up at oxxo stores ( The Mexican convenience store chain), they have stores all over major cities in Colombia. To top up, ask for Tarjeta amigos ( airtime vouchers) since most people here don't understand English.
All you need to get your sim card registered is your passport, hostel/hotel address, and your phone's IMEI number.
Compared to most Latin American countries data is more expensive in Colombia. The largest data package you can purchase from Claro for instance is 2GB for 42900 cop ( $11) valid for a month.
1 GB data costs 20900 cop and is valid for 15 days.