There are also some other "rule of thumb" items I go by in preparing my evaluations - just as an appraiser would do. You want to make sure you have someone do the evaluation that knows what they are doing...
condition, subdivision trends and much more. Any Realtor that just uses size and location will most lickly not remove the forclosures, and short sales.
Any Realtor in the area will assist you without obligation , we do this for good will.