Coil Pack for 2002 Dodge Stratus

I have a 2002 dodge stratus and for a while now it had been shaking, until a week ago, it started shaking badly. finally the check engine light came on and it said that I was having a misfire of the spark plug. I got a tune up and everything was fine for a day. the check engine light came back on with the same reading. Could it be that I need a new Coil Pack (that's what they said it might be) and they said that those run about 135.00? Is that right?
Help!

Also check into replacing plug wires if they're getting up there in mileage. Some places don't replace those in a common tune-up. They cost anywhere from $25 to $30. The cost for the coil isn't to far off. I found them at Parts America website from $85 to $120