Shopping Cart Plugin

Here is what I need to figure out how to handle. I need to build a site that sells t-shirts to high schools. Each school should be able to go to the site and click on their state and school to find their schools shopping cart items. When the deadline to order the shirts has hit the expiration date we need to be able to download the orders for that school ONLY. What is my best way to handle this? Its like having multiple stores up at the same time.