1. Your accountant is not the person you go to for Legal Advice. 2. Unless the purchasing agreement is signed by Both Parties it can still be amended. 3. The prospective buyer may have submitted a template purchasing agreement they obtained online. Have an attorney who specializes in business law review and amend the agreement to protect your intellectual property and to maximize your price. You can sell your company once, so don't risk cheating yourself. Get legal assistance.