We came to a few terms on our end and wanted to start a negotiating process but the broker said he refused to present our letter of intent.

The activities must also be for a fee or something of value, or with the intention of collecting a fee or something of value.

My intent is to expand into doing more real estate flipping. 

First form a relationship with a Realtor you trust; and second it is their job to run comps for you as long as you have an intent to do business with them. 

I currently am the owner of the property and purchased it 3 years ago with the intent of it being a rental property one day.

list=PLASIT_lNqzXlrN...get a "I BUY HOUSES CARD", go network, find transactional funding if cash buyers can't buy, that should be your "intention"And get licensed in OH@Bill Gulley@Jay Hinrichs

I am looking for something that is a B- or C+ property in a A/B area with value add potential.I understand that deals listed on the likes of Loopnet will not be the good deals, and that those come from building a rapport with brokers.My question is, how many brokers do you tend to contact when beginning a search with intent to purchase, and how often do you follow up with them.  

What I think is more detrimental to your case though is that from what you say your intent in building that house was primarily to resell it.  

Because it was their intention to pay it and it never happened?

I would speak with a lawyer to be sure you are familiar with all state laws and procedures, use cash for keys or any means necessary to have him permanently removed (keep your thoughts and intentions to yourself), and send your new tenants a message that you will not put up with this or anything like it and will be providing them with a  better quality of life going forward.