Wordpress Plugin Development

Must be an expert a PHP and have experience in Wordpress plugin development. Please link to plugins you have created. Please no theme portfolios this is for a Plugin. Project description: This is the plugin I would like to re-build or to use as an example. Wordpress Simple PayPal Shopping Cart The reason I am interested in this plugin over other more complex and more functional shopping carts is the 'custom fields' in Wordpress. No other shopping carts work with custom fields for adding product as post. I use a csv uploader and it will automatically populate the posts with hundreds or thousands of items. Having products as posts allows other plugins and all the benefits of Wordpress to manage and optimize the store. The code is small and simple and I have no interest in product management on the website. As of now the plugin has limited function with product variations, quantity and pricing. All short codes would have the product # to link them together. A simple product with only price: [ez_cart:#PRODUCT-NUMBER:price:PRODUCT-PRICE:shipping:SHIPPING-COST:end] Product with variations: [ez_cart:#PRODUCT-NUMBER:var1[VARIATION-NAME|VARIATION1:PRICE|VARIATION2:PRICE|VARIATION3:PRICE]:end] Endless variations all linked together with product #. Also the two quantity inputs, drop down or number. [ez_cart:#PRODUCT-NUMBER:quantity-box:1-15:end]min and max numbers. or [ez_cart:#PRODUCT-NUMBER:quantity-drop:1,2,3,4,5,6,7,8,9,10,11,12,13,14,15:end] Also the plugin would need more id/classes for css. All branded with ez_cart. The plugin would need to be built with these other modules in mind for the future: Discounts PayPal Pro, check out page Shipping Check boxes to complete checkout, like "yes, I have read terms and conditions", newsletter. Digital downloads Mini basket as widget Layout options You can include these modules in the bid separately. I will do the graphic design for the cart and I will create a mock up of the settings page. To be considered you MUST link to plugins or php projects, NOT a list of themes for example websites. Thank you.