The $200 flat offer is the assumption doing the most work here, and it almost certainly undervalues what you are producing. One closed deal funds months of that fee, probably much more depending on the wholesaler's margin. Before you decide on a structure, you need some sense of his conversion rate on your list. If he closes one deal every six months off your filings, $200 is defensible. If he closes one a month, you are leaving real money behind.
The three pricing structures each carry a different risk profile for you.
Flat monthly is predictable and administratively clean, but it caps your upside and transfers all the deal risk to him. At $200 he is getting a very good deal if the list converts.
Per-filing pricing ties revenue to your input volume rather than your output value, which is the wrong anchor. Your list's value is not in how many filings you pull, it is in which ones turn into deals. Per-filing rewards you for a large county with lots of noise and punishes you for a tight, well-filtered list.
A percentage or referral fee on close aligns your incentive with his, but it requires him to self-report, which creates a trust and verification problem you cannot solve without a formal agreement. A licensed professional should tell you whether any fee-sharing structure in your state requires a license to receive. That is a real question here, not a formality.
The practical move before any pricing conversation: tell the other two wholesalers that the arrangement is changing. What they say tells you something about how much they value the list. If both push back hard, you have leverage. If neither cares, that is information about conversion rates you should factor in.
The structure I would think through most carefully is a tiered flat fee per subscriber, something like $150 to $250 per wholesaler depending on exclusivity. What does your data show about which zip codes or filing types are converting for him?
