Social Coupon - ffering your customers a discount if they Facebook Like, Google+1 or Tweet about your site

ffering your customers a discount if they Facebook Like, Google+1 or
Tweet about your site
Social Coupon

gera ideja, rekomenduojama taip daryti ,bet gal yra mokamas
extenmsionas su geresne implementacija ?

http://www.opencart.com/index.php?route=extension/extension/info&extension_id=13863