Mark, I ran sales for years, as well as being as salesman in the electric sign biz. IMO a fixed 10% doesn't give you the flexibility in your pricing. A lot of factors come into play. For instance, how much support is needed for your salesperson? Are they clogging up the graphics folks with excessive drawings? Are they putting enough time in the job to handle their customers? Are they out in the field peddling for business, or are you supplying leads from your advertisements? I still sell, and run the company. IMO no salesperson should ever get a base salary after 3 months. At 3 months, either they are going to make money, or they won't. Salespeople get paid when I get paid. When I get a 50% deposit, they get 50% of their commission. When I collect the balance, they get their balance.
For a salesperson to be successful with me, they need to put the time in, 40+ hrs a week. They need to be able to look at a sign location as an installer.They need to understand fabrication, and city codes. They need to be out of the office and selling signs 50% of the time. They need to handle their business with nominal company support. If they meet this criteria, here's what I believe is fair compensation. $600 a month car allowance, company phone, Health care, paid holidays, and vacation (based on their yearly income level).
10% commission = selling the job at company standard pricing, with all mark ups at full ratio. When the price drops, so does the commission percentage.
For salespeople who need a lot of office support 8% at full pricing. Then drop rate as price falls.