The easy way would be to purchase points from an established rewards program and give them to your clients.

For example, in Canada we have the Air Miles program. Businesses can purchase points and give to customers. Users can redeem the points for rental cars, hotels, air tickets, etc.

Look for an established program in your country that offers rewards your clients would enjoy and contact them to see if you can buy points in bulk and redistribute them via an online portal.

Cheers

David Barnett
www.DavidCBarnett.com