Have you taken a look at an affiliate network like Maxbounty? They publish their current rates here: http://www.maxbounty.com/showoffers.cfm

If leads are delivered real-time and exclusive, prices go up. It also matters what the traffic source is: personally I have only generated leads from search engine traffic as that is some of the highest quality you can get. Finally the more information the lead submits, the more valuable it is.

You might get reasonably current, but accurate is much more difficult because of all the contributing factors that go into it. That said, you can start with what you have access to already. If you know that your offers in a sphere are taken by 20% of the people who elect to view them, that can be a starting point. If you visit trade shows and you ask enough people you can get a sense of conversion rates online. They vary a lot based on the the reasons (and search terms, or prompting) why users choose to a view an offer. Once you get a rougfh estimate of the conversion rate, visit adwords or get a temporrary sign up at semrush or spyfu and enter a seed keyword for your industry segment and find out the average cost/click. - do the math - 20 bucks/click on a 20% conversion rate would be a $100 CPA

This would be virtually impossible to identify with a high-level of precision. So many variables in play here and obtaining a CPA benchmark with this level of specificity is no feasible.

The best reco I can give is to simply evaluate what the traffic cost would look like to acquire relevant traffic to your domain and then apply assumptions around contact submissions and the conversions. I’d suggest these would be extremely low based on the high-level of qualification, possibly in the 0.05% range as a percentage of the traffic generated.