I could see a lender getting a BPO completed, but unless there is a pending buyer, I see no reason why there would be the expense of an appraiser.

I suggest this as your first step because it could take a while pending on credit and/or finding the right lender.  

If i was in your shoes, I would call the listing agent and tell them you have a legal contract  to purchase with the seller and to change the property from "Active" to "Pending" in MLS.  

1 more thingPull pending comps in the area as well. 

If it all checks out and they submit a holding deposit, I refund any other pending app fees and get  lease signed.If I don't charge a fee, I will get prospects that will hope I don't actually do the checks, and will be out $29.45 per applicant that doesn't pass.  

Did you agree to pay back by a certain date or is it ambiguous pending closing?  

The granite was the last pending item for us to finalize our kitchen paint colors etc.  

However if there aren't enough comps that fit those constraints (usually we want to find at least 5 or 6 similar comps) then we have to either expand the search area or the period of times (but no more than 1 year) when Im performing an unofficial BPO (aka ARV) for myself or an investor friend/client I will include pending properties.

The longer the DOM, the more open to negotiation the seller will be.3 In a seller's market, as a buyer, you know when to make your offer based on the number of, the frequency of, and the dollar amount of each price drop.4 If the DOM includes a number of Pendings that were re-listed, it tells you a number of things...not the least of which is at some point, the seller is going to give in.JV

I agree with Adrian, again....as mentioned states have set provisions for contracts pending in the event of the loss of an agent or broker's license.