Did they request you do the BPO to handle a REO or did you do it for a Short Sale.
Sometimes on the Short Sale it they seem to be in too deep they will want verification. Have another agent in your office do one and if you have a friend in another office that does not mine have them do one and see if they come in close. Send all three to them.
I did have a Short Sale that just close that there were no comps when I first sent in the paper work, Not in the subdivision and not with in a few miles. There were with in 5 miles but in our town the other side of the frwy makes quite a difference. I went to the subdivisions and found out what the new homes were selling for and how much they were paying and giving to do it. They then took the BPO.
Remember an appraiser goes 5 miles out when they can not get comps from same neighborhood. Next is the closest similar neighborhood.
You have to attach an explanation letter to the BPO as to why the comps are limited. Most asset managers require that the comps be within a specific radius of the subject property. It is tough sometimes. They would just have to pay for an appraiser or accept yours.