Startup Idea : Social Sell

I am really into buy and selling items, and always get frustrated when I miss a good deal, especially if it was someone I know who had the item i was looking for. So i have created a social selling idea, where you take pictures of items with your smartphone, give it a description and a price and a category and post it. I automatically gets posted to our online site and people search for items and can find yours. the twist is that when your post it automatically posts to your social networks as well as to the people on the app who follow you or have bought from you before. It is similar to a pinterest and an instagram but with classified ads abilities. this app is all mobile, and you also receive alerts from anyone who posts items you are looking to buy.. So a social buying and selling network then starts to form as well