How much to repair a blown head gasket to a 1997 ford contour?

I live in NC have a 1997 ford contour with 153,000 miles, I bout it from craiglist for $1000 about 3 in a half months ago, the car work very well until i seen white smoke. My mom and grandad said that the gasket blew cause the car ran hot. I want to know how much will it cost to repair? or should i just sell the car for about $500 and get a brand new car and make payments. Please give me honest opinions