Less than Reg fee. IMO.
Unless you live in Colombia and do business there, there is no reason to register a .CO domain. Come to think of it, if I lived there I would still probably use a .COM.
The .CO is yet another ccTLD that has recently gained attention via, I guess some pretty good marketing hype by the registrars. Don't buy into this hype because, just like .MOBI, .TV, .TEL, Etc., Etc., (yes, I know those are not all ccTLDs. duh) once the new wears off, the registrars will jump on a new TLD and milk it dry too. Then you, the registrant will be the one left holding the bag.
In my viewpoint, you should grace delete this and all other .CO domains in your account and all others who read this should do the same. As a matter of fact, I sincerely believe that everyone who hopes to own investment grade domains that will hold their value MUST become biased toward .COMs.
Hopefully, someone in their right mind will read this and a light bulb will go off in their heads. Go take a look at the history of .ME, .BIZ, .TEL, .TV, .CC, .SC, .WS, each has its own history with one common thread. They were once the next best TLD that would catch on and become a household name. It didn't happen with those and it CERTAINLY won't happen with .CO.
Do yourself a favor and think about what I'm saying. Save yourself some money and jump off the .CO train at the next stop. IMO.