I like it!

Only other suggestion I could make would be for crafters. You select your final product and it populates the shopping cart with all the components needed to make it. Then you go through the cart and prune the materials you already have and don't need.

All the cheapest materials would be automatically selected so, in the end, all you say is, "I want enough materials for three synths" and it purchases it all for you, moving it into your inventory.