database compilation

i need the following: i need to compile up to 6 databases, and i need to be able to pull the information and pull packing slips based on the pricing information in the databases. the database also needs to have internet connectivity to be able to grab information off websites such as amazon and ebay. must be able to scan upc/ean/bookland barcodes into the application to find the information in the database. the database needs to be as small as possible. must be able to update the database with new information (around 500,000 records) VERY quickly. must also be able to use this information on a website in order to purchase items from companies and individualsusing the database...reverse e-commerce must be able to manipulate the information in the database on the fly using over-ride buttons. i currently have a working model of this application but it needs significant upgrades and re-working. ## Deliverables -