How do I get paid for bringing a buyer?

[Jonathan Guerrero]

So I might be closing on my first deal today.  I called a bandit sign and introduced myself to the wholesaler.  I told him I'm new in this business but knowledgeable and I'm looking to grow my network and possibly partner up on some deals.  He had one. I told my buyer about it and negotiated.  He's buying at 90k but there's no room for me to buy cheaper and reassign it at 90k. I know we unofficially partnered up and it should be a 50/50 split by bringing a buyer but I know that won't happen. 

I still don't know what he has it under contract for but my guess is 70k max 80k.  What would be a fair cut for me?

How should I approach him about this?

Don't want to sound overconfident but I don't want to get taken advantage of either. 

Your help is greatly appreciated.