If it's just a list, I would pay roughly the cost to create a similar list, inclusive of your time, incremental data costs, paying freelancers to scrub, etc. I'd discount the value based on the age of the list and relevance to my target industry. I'd pay more per item if the contacts are validated and/or someone actually researched the companies. I would not pay a success fee for just a list.

For the record, I wouldn't even ask for a few of sharing a list with a friend after my search closed. List building is relatively easy and cheap; converting contacts to deal opportunities is hard. And I like helping other searchers.

If there are specific warm leads (i.e., qualified on size, business quality, and intent), I would agree to pay a success fee in the 0.5-1% range for an exclusive intro, assuming it's not a business with which I have already engaged.

If the connection has a truly special/proprietary relationship and is going to put in real work advising you on the transaction without a conflict of interest, I would go higher (but not more than a few %). You should model the fee as part of your deal expenses and you need to be able to hit your return targets after accounting for the success fee.

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