The BPO is designed to guide the bank as to whether or not the offer is reasonable. If as you ask, the BPO comes in a lot lower than the offer, the bank may either chose to counter, or reject the offer. Banks typically have rigid guidelines setup which will dictate how they respond. Unfortunately they all differ so a definitive answer very difficult to give.
The bank will share the results of the BPO with the investor who owns the loan on the property. The investor will direct the bank what to do with the results. There are only three options, accept, reject, or counter.
How long this takes is always a challenge in this industry.
Your agent can keep you informed on the progress of the transaction.
The bank is trying to obtain value on the property. Typically, the bank will accept or counter the contract after they get the BPO back. This would probably happen within 45-60 days.
Joanne Spivey, CDPE, The Buyer's Best Realtors, 301.874.5100
The BPO is normally sent to the bank/investor for analysis to make a final determination of value on a property. If your offer is higher then the BPO suggest, that is definite plus, but does not always translate to quick response or approval of a short sale.