Welcome to the Bonneville Forum!
Please add your year and trim of your vehicle to your signature line. That way when you start asking questions in other areas of the forum, we all have a better idea on how to assist you. Click on "Quick Links" above, go down to "User Control Panel" and then click on "Edit your Signature" It'* pretty straight forward from there.
The serpentine belt is not that difficult to replace yourself, but if you need a mechanic to replace it, it shouldn't cost your more then 30 minutes of time if you already have the belt.