I can refer you to several third party platforms that provide this service: www.referralsasquatch.com allows you to create an incentive based sharing system, www.sweettoothrewards.com is similar but more tailored to a full 360 loyalty program. Additionally, www.referralcandy.com has a different form of pricing that may suit your needs because it allows you to pay as you go; with no setup fees. Hopefully these few recommendations will be enough to get you atleast considering different options. Feel free to call me with any questions or implementation advice.