For us, we have paid based on a commission payout. We generally give the sign up payment to the sales person with a bonus if they stay for more than 3 months. I suppose you can consider it almost like an affiliate program. I'm sure there are a lot of other ways you can do it, but I feel the best way to pay sales people is based on how well they do and how much effort they put in. So a commission type payment seems best.
SolaDrive - Enterprise Managed Solutions
Specializing in Managed SSD VPS & Dedicated Servers in US & UK
Visit us at SolaDrive.com