I have never hired a Designated sales person..
I preach to my workers that If they get me the lead into an account i will give them a 5% commission on what i take in on the account..(after material). So all i have to do is price it all out then turn it in. I have never put a limit on the amount of commission that i'll give them other than 5% PER account. Commission on accounts only last for the FIRST year of service. If we renew the contract you're done with commission on that account. This leads them to get more accounts.
This is completely optional and open to all of my workers. Whether they take that opportunity or not is up to them. But for the guys who do take the opportunity, they make their hourly/salary plus an extra $XX Bucks per billing cycle.