CG-Amazon, part of my CG-PowerPack, does a lot of the major Amazon linking features — and allows you to build your own internal database of products. It isn’t a ‘shop script’, at least, not yet…
The next version will have a drop-in page template for a products ‘area’ on your blog, making it more shop-like. If there’s enough demand for a more commercialized product, I can certainly work on the remote-cart features Amazon exposes as well.
So, the real question back would be: what do you mean by an “Amazon store”? Do you just want a shop script that sort of ‘hangs off of’ the blog, do you want something integrated with your blog where you can link to product pages (on your site) from within posts, do you just want to be able to post wishlists or other lists of products on a custom page, or sidebars?
‘store’ and ‘shop’ mean different things to different people… on the web, they can range from a virtual storefront (i.e., emulating your own version of Amazon itself), all the way to just having the ability to include product links…
-d