I am looking for a shopping cart to implement on a simple website instead of the default paypal cart that is used with their add to cart buttons (I don't like the non-styeable new tab/window cart). However, I really like the ability to simply add the buttons to existing pages. I do not have a lot of products and do not want to deal with a storefront and complex templates.

The main features I need:

• Self-hosted
• Easy to implement with existing website (copy and paste button code, etc.)
• Ability to have variations on one button with different prices (dropdown with sizes, colors, etc.)
• Ability to track inventory and disallow out of stock orders
• Ability to pass cart details to PayPal Website Payments Standard

I have seen most of the large storefront options: oscommerce, zencart, cubecart, opencart, prestashop, magento, cs-cart, lemonstand, etc. but these are way more than I need. I don't need the storefront or customer accounts or templated pages, etc.

I have seen e-junkie, which is not far off from what I would like, but it is not self-hosted and I would prefer an in-site cart (or dynamic overlay cart) rather than a lightbox or new tab/window cart.

I also love the paypal minicart and its implementation, but there is no way to track inventory.

So, does anyone have any recommendations that might meet these requests?