$10 isn't really enough to get people looking for you. I think that anyone that would refer you for $10 would refer you for free.
I have done some programs in the past with my plowing services and received a few referrals. I have also done no programs and received the same amount of referrals. You may be better suited investing the $10 in sending the customer a thank you card following your services and remind them that most of your business comes from referrals. When you treat them well they like you and are glad to help you find more work.