What are repair costs to replace leaking oil seals-Breather cleaned, still leaks on 2001 Volvo V70

Leaks about 1/2 qt oil every 600 miles. Seems to be coming from behind pulley. Cleaning/replacing breather out did not help. What should it cost to have leaks repaired. Non turbo '01, V70
Thanks

Asked by for the 2001 Volvo V70
WHICH OIL SEAL ARE TALKING ABOUT THERE ARE SEVERAL