In my experience incentives for referrals don't work that well. Particularly if your referral sources are small businesses. The small amount they'll get won't compensate the risk of upsetting their clients. I'd suggest you find a way to make it easy for your referrers to introduce you. Think of a service they could offer their clients you could provide for free: website review or a 1/2 hour consultation. Or a product they could give away that's seems valuable like a complimentary webinar, or white paper or report, or checklist. Help your referrers look good in front of their clients.