Copy one Amazon Seller Inventory to another Amazon Account

Copy an Amazon Seller's Inventory (All Books) to our account. Our competitor seller account has about 1,000,000 book inventory. I will need to copy each item into another amazon seller account (my own), I do not have access to the account of the seller with the inventory so you will have to use the ISBN number. Perhaps putting them all in an excel file first would be easy? When Bidding explain if you understand the project and what I am asking you to do, how long it will take to transfer 1,000,000 book inventory.