Typical finders fee for commercial property

[Mark Gliebe]

What is a typical finders fee for an investor for an off market commercial property?  Is it percentage based, flat fee, or what?  Do you ask for a percentage of development project?  Also how do you prevent someone from going around your back?  I know investors are constantly wanting deals, but don't have the resources or the time to go find them.  Thanks look forward to any an all advice.