How likely will a debt collector sue?

Ok i hear lots of diffrent things. I hear that they will not mess around with amounts for under 7500. It cost too much for them. I also hear that it is under like 500. I opend a credit card and had a balance of 3000, this was 5-6 years ago, i ran into some heath issues and could not pay. I did not recived any collection calls till now from a lawyers office in N.Y. The demanded it in full, I just went through a divorce and i dont have all of the money for them. Now why is a lawyer from N.Y. contacting me i live in Michigan. Anyone every been down this road.