Customize Gripsell group buying script with custom features

Need developer with extensive skills in gripsell group buying script to create some customizations ranging from graphics to reprogramming the referral system and email marketing module to use Mailchimp. Also need to add deal tags and add a tag search engine as well as a category selection menu. More information will be provided in private message once qualified. Please bid only if you have extensive knowledge in gripsell and cakePHP.