I requested that the counter be put in writing in the same format as mine through an AOE, but my realtor mentioned that is not the standard and this is typically only done when negotiations are complete.

There is only handful list of larger lenders offering non-recourse loans to IRAs and 401Ks, but nothing prevents you from finding a private lender and negotiating the terms with them.

How do you negotiate terms with these contractors?

It all comes down to whatever you can negotiate.  80/20 has worked for me in the past.Yes, profit is the amount of money after ALL expenses are paid.  

Do I need a real estate agent for a seller financing negotiation or is this something that I should do on my own?

How did you find this deal and how did you negotiate it?

I wouldn't give too much thought to his financial position, because it could go any way; he might be a billionaire because he's a shrewd negotiator and enjoys pushing back, and at this point, he doesn't NEED to sell.

How did you find this deal and how did you negotiate it?

How did you find this deal and how did you negotiate it?

How did you find this deal and how did you negotiate it?