Figure about 8 hours of labor on the low side, about $400 for the converter (average priced...not sure which transmission you have...). All told - probably $1,500. At that price, I'd probably investigate the cost of a remanufacutred transmission, including the torque converter.
My first question would be why do you need the convertor replaced. Without knowing whats going on with the transmission, just to R&R the trans to replace the convertor is about a 6 hour job flat rate. So depending on the shop hourly rate it would depend