Most come in at around half that, but if windows need to be replaced, or if the exterior doors do and need to be custom sized, it can get expensive quick, so $10k is a safe negotiating number.

But, in my opinion this sounds like an angel investor/customer for you, or somebody really trying to partner with you.

Someone who understood the different rules (DOS/Local MLS rules/State REALTOR rules/national REALTOR rules) as well as customs.

My question is what happens if they back out before closing and what if their taste is too custom.

I will do some looking into customer relationship management (CRM) software and see what I can find.

One thing about Lowe's is that they take their customer satisfaction very seriously.

Wikipedia: "Customer relationship management (CRM) is one of many different approaches that allow a company to manage and analyze its own interactions with its past, current and potential customers."

If you want, you can take the line of "I work for a company that...." so they don´t pin anything on your personally, but a corporate entity. 

In the beginning I had a ton of questions and their customer service whats informative in their responses.

Usual/custom in OR is damages limited to E/M and decided thru arbitration.Does specific performance happen?