Please send me examples of plugins you have built, not themes. 

Project description:

This is the plugin I would like to re-build or to use as an example.
wordpress simple paypal shopping cart plugin

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 so all products would be manually entered. The code is small and simple (one page 28KB). I have no interest in product management on the website, i will use desktop apps.

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|V ARIATION3:PRICE]:end]
Endless variations all linked together with product #.

Also the to 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 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
short code in custom fields

I will do the graphic design for the cart, and send you a mock up image of the settings page.