Order from Amazon

I need a VA that will be available every day between this hours : 21:00 - 05:00 UTC TIME .
The job is simple - wait for order from my eBay account, go and order it in Amazon / Walmart / Overstock. Gift cards will be preloaded. Need to know how to handle add-on items on Amazon, be accurate, look the other stores (after training by me) for a better price.