Freebies For Loyal Customers

I open up this matter not only for myself but also to those who engage in offline business. Our business is related to Mobile Phones, we also display cheaper one which is affordable for the masses but we concentrate in Electronic Reloading, SMARTMoney remittance center (sent and claim) and also Cellphone accessories.

Within 3 years of operation I am now connected with loyal customers. I want to give freebies to all of them. I am thinking what kind of freebies I'm going to give. Can you suggest me anything that can make them happy? Of course it will also encourage them to continue their loyalty with us.

Please help me guys!