My friend had sent me a message that said, "Hey, I had to get out of Cartagena. Long story, but drugs were involved. I'm up the coast, a little north of Cartagena, come up and meet me here. I'll tell you more later." I honestly thought for a second that he might have been joking, but then I remembered just how accessible drugs were down here and how easy it would be to get into a "sticky" situation.
About a week or so later I meet up with him and got the full story. Turns out he graciously accepted a similar offer to the one I mentioned in The 5 Best Things to Do in Cartagena. The difference was that he was alone and it was at night. The guy told him to come with him to his bar where the drugs were. The bar was up a small flight of stairs with body-guards inside the entrance. The guy asked him to sit down while he called "the guy" to get the cocaine. He had asked for a small amount (1 gram) and had been told that the price would be around $5-$8. When "the guy" showed up he looked like a drug kingpin and demanded that he buy 5+ grams at a price of over $500...
From there my friend felt like he didn't have many options because he had been told that if he didn't pay that the guards would beat him at the door. He had a small fortune on him at the time but didn't want to pay the outrageous price so he said that he would need to go back to his hostel, get his card, and then go to an ATM. Basically trying to stall and get out of the situation. After lots of yelling and threats "the guy" agreed to let him go as long as his assistant followed him to the hostel and ATM to get the cash.
After going to the hostel and ATM he managed to tell them that there was a limit to the amount he could withdraw in one transaction at the ATM, so he paid slightly less than what they had asked, but still an outrageous amount in Colombia (I've heard people tell me that they went on a "tour" into the jungle and made their own cocaine for about $35). He left on the earliest bus the next morning and didn't sleep all night. Even in Medellin (14 hours in-land) he was leery of anyone offering drugs and being out late at night.