My attourny is also my sister so I don't get scamed very often, but I know how much it cost if you're not in a similar situation, as I've been there myself.
I agree that going to the magazine would be the best way to procede, and also the certified letter would likely be worth a try.
If you did in fact subscribe to the magazine I would ask for all the back issues that you havent received and suggest to them that if they don't either honor there end of the bargain or get the collection agency off your back that you will paint a negative picture of them all over the internet as well as contacting the BBB.
You might even name several hunting and shooting related forums in your letter just to help them understand how much you could potentially hurt them.
But most importantly, if you did in fact order the magazine, and you have received what you were entitled, then pay them what you owe and quit screwing arround, otherwise see above. Glenn