Magento Import Product Data Plugin

We're currently looking for a developer to create a Magento plugin that allows us to import the contents of a SQL file (from a cash register system) into Magento. Allowing the store inventory to be updated (new products added / quantities changed / prices changed) with a simple SQL import. And this would be done daily to align both systems. Some important details: -> The SQL files are quite large and contain information that has to be filtered out. -> The store features quite a lot of configurable products with the option to choose (shoe) size. So the plugin needs to be able to create/update configurable products, together with the related simple products. User-friendlyness and ease of use are key. The plugin needs to reduce the inventory updating process to a minimum. The developers own input on how to tackle the project is welcome. Experience with magento and this kind of work is valued. The project start is for next week, as some key information has yet to be gathered. When bidding please mention estimated work time. Kindest regards, WebKrunch