Create Solution Bot for instant purchases (eCommerce)

I am looking for an automated bot that instantly purchases new merchandise, through e-commerce sites, as soon as they are released for purchase. Similar to a ticket bot, but only with goods sold through various small online stores, such as big cartel sites. Often the goods I need to secure for my business are sold out before I have the opportunity to purchase. This would have to work on a range of small online stores, it will not be required to work on large, complex e-commerce sites. This program would have to be run on OSX