I realize refinancing can also have significant costs...Another take on that scenario would be to pay down $5K in equity over a year or two and then refinance, pull out the equity and return it to the lender to fulfill your agreement.Could a contract be structured around this type of idea?

He/she has fulfilled the terms of your agreement and you have not.  

He kept adding more concessions on for me to fulfill that the "buyer" demanded.

If he signed a lease agreeing to late fees and then crossed them out of the extra copy you sent after you purchased it, then he is legally responsible to fulfill the original contract and his crossing out malarkey doesn't matter. 

Being as though you already see red flags you want to be able to secure your EMD should the seller not fulfill the demands in the contract.

This is hat the security deposit is for, as security to fulfill the contract signed.

@JD Martin,I am all for building people up and supporting small businesses (I have had multiple) but if you claim to be a tax strategist and are paid for that service, it should be that persons fiduciary responsibility to fulfill that service.To answer your question, I had two other CPAs look over what Natalie prepared before I signed them for filing. 

A property is secured by a note and deed of trust which give the lender the right to foreclose if the investor doesn't fulfill their end of the relationship.Also, an insurance certificate can be made out to the lender so they are protected with insurance in case of a total loss.

Does anyone have experience investing in or operating a fulfillment center?

Which could also land you in trouble because as a mortgage broker, you have a fiduciary duty to the borrower and that conflict of interest could result in you not being able to really fulfill that fiduciary duty properly.