I second Gary's post.  Are they working with a Mortgage Broker to get refinancing?  
If the Mortgage broker works with a lot of investors they should know which appraisal company to get in there.  If it is the bank appraising it straight off I would expect the value to be off by 5 - 10% .
If your friend wants a preliminary evaluation based on the market.  So he has a number to give to the bank Let me know and I can  work some numbers for him.
Regards,