How can I guess the value of the note I am creating?

[Will R.]

Hello all! This is my first experience creating a note on a sale. I have a $600k property in Austin, Texas that has a house on it that is used as a daycare. I want to offer a first lien for about $250k to an investor who will buy the property. What terms do I need to create to make sure I can sell this note immediately for at least $250k? What is the best market/website to sell it on?