Online Inventory Management System

We need an online inventory management system.
Today we have an e-commerce platform with more than 5000 product and almost 30 different vendors and growing. The inventory (stock/price) is never up to date because it is very difficult (not user friendly) for vendors to use the admin interface in Magento in order to update all their products.
We need a user friendly web based gui grid or spreadsheet like. In just a few clicks vendors should be able to easily update they product detail and inventory.

You understand that the usability and the UI design is the main requirement of this job.
We would like to use : mysql, php, html5, javascript, ajax, ....extjs???
The db model is very simple less than 10 tables.

Required features:
- Vendor log in
- He is able to see his products in a grid (with filters, sort…)
- He can edit products (name, description , photos, price, stoc)
- He can remove/add new product
- he can export the grid as Excel or PDF
- He can import from csv multiple products in just one click

Examples of grids :
[URL visible pour les membres Pro]#!/example/writer/writer.html
[URL visible pour les membres Pro]

We do not really care what framework you use but it should be in PHP, HTML, JS universe. Just make it fast and simple to use.

We can give you detailed specs later if you get this job.

We need a Ninja coder here. If you are not a Ninja please do not apply. It will save us some time.