First Timer - "Finder's Fee" Arrangement

[Keith Meyer]

I'm currently in a situation where I'm looking to connect an interested Investor with a commercial property Seller (who is actually a Wholesaler herself in this case). What's the easiest way for me to collect a finder's fee/referral fee for helping to connect these parties? 

I'd prefer to avoid putting the property under contract myself and doing an assignment, since there's already a Wholesaler involved. This seems like a transaction I hear about being executed on BP all of the time, but I haven't found a simple explanation or template for how to formally execute the process. I don't currently have any business entity/LLC, so that would probably eliminate the option of implementing a consulting contract and charging a fee for services. I live in Cali so I'd prefer to avoid filing for an LLC until I'm fairly certain the deal would make sense for both parties. The property is located outside of Cali.

Is there a simple Finder's Fee template which contains enough protection to handle these common transactions? What's a reasonable fee to collect on a ~$1.5 million transaction?