Just an update for anyone else who may be travelling there - Yes, they do refer to them as E tanks and the do have the same CGA-870 connectors.   However, tanks are difficult to locate, as most suppliers only have oxygen generators/concentrators.   If anyone goes to Colombia send me an IM and I can give you contact information for who I finally found who could provide tanks.

Lastly, I stayed at Casa Don Sancho "hotel" (more of a bed and breakfast), and they were FANTASTIC for helping me with the oxygen situation.  They went and picked up the tanks on a Saturday for me so I'd have them upon my arrival, fronted me the money for the downpayment to the supplier, and dropped them off again.  They went way above and beyond what I would have expected a hotel to do!  I was very impressed!  Overall it's a fantastic place to stay!

Matt