Build a simple solution to automate eBay and BigCommerce shop sales via Kunaki

I sell various software CDs on eBay and my own website and have moved to them being created and shipped by Kunaki. I currently have to manually enter the shipping details from eBay and my website on the Kunaki website, each time a sale is made. I want to stop this from being a manual task so I can just have the items shipped when paid for. I'd prefer the solution to be cloud based for availability and also be editable by me if needed, to cover the times when a new product needs to be added to Kunaki. I'd also like it if I were prompted somehow, if the item that was sold wasn't available in my Kunaki catalogue. Other potential features and points to note are below: - All payments are via Paypal currently - the solution could email the buyer with a message when the item has been sent to be created - another message for the buyer when it's been shipped would be good - if it supplied the shipping tracking refs to the buyer in the email that would be great too. - if it could update the eBay status of the item to shipped when its been dispatched by Kunaki, that would help too I'd welcome any other thoughts on how this can be done in case I am missing some useful options.