You didn't say what kind of company you have. My experience is with tech companies where the sale is very complex. So, I will give you my thoughts from that perspective.
Pay them a base of what you'd pay a mid-level person at your company. Then give them HUGE upside potential. I've seen software startups pay $50k base and $500k OTE. If your person makes half a million bucks and is the highest paid person in the company you will be wildly successful.
A great book to read is "Selling the Wheel" which is a parable about a tech startup (the guy who invented the wheel) and all the various ways to make sales.