serpentine belts on 2005 Suzuki Grand Vitara

I have been told my serpentine belts for both Alt and AC are beginning to crack and need to be replaced. Could these be worn out in just 5 years? If so, does it make sense that the estimate for parts and labor totals to @ $120.00?
Thanks! KIM

Asked by for the 2005 Suzuki Grand Vitara
Yes they could need replacement in five years time and $120 is a fair price for 2 belts installed