The lab I use (Epperson Photo in Oklahoma City) does all my work via the mails as I live about 40 miles away. Here is a link to their web page where they list the prices for doing what you discuss.
http://www.eppersonphoto.com/digserv.asp?categoryID=14
Note, that the scans run a bit contrasty and they sometimes cut off the edges. They are pefect for reference but not sifficient to print much from.
Hope this helps.
regards
mark sharfman