Repair cost to replace corroded heater coolant pipes to the rear? on 2004 Kia Sedona

Apparently my heater coolant pipes to the rear heater have rusted and blown. What is a ballpark figure to have a mechanic fix this?

Asked by for the 2004 Kia Sedona
I had the same problem. Eventually it resulted in overheating/head gasket. Estimated cost to replace heater coolant pipes = $400 IIRC. I decided to have them bypassed instead. People in back have to deal with the cold now. Its not too bad.