You might try the Appraisal Institute in Chicago. You are going to find that cap rates vary considerably depending on type of property and locatoin as do mortgage interest rates depending upon the type of property. Using an average cap rate for an area can be dangerous, or when using a cap rate for one type of property with a different type. Sounds like you are on the right track, just a matter of finding a good source. Reis might be good as well. Good luck.
Dec 7, 2012