Compare prices and find products

Hello, I would like to customize a technology on the Internet. I imagine something like this: An online system where people can search and compare prices of products in a particular city, and the website indicate the stores and malls where you can find. Seen from another angle, a consumer who is shopping one product and not know which stores sell the product they want. For example, I want to buy a tennis racket - I go to the site, I research, and it shows me which stores have the desired product, and what malls which can acquire them, comparing their prices. The registered stores, if they hire our services, may have better ranking in research, and can develop promotions for customers with a unique and targeted advertising. All activities by consumers may be shared with facebook, and can even ask your friends the best indication products and places with cheaper price. Or just showing in your facebook your research and purchase of a product Or, for example, sync with facebook if I'm at the mall looking for a tennis racket - and ask indications. I think, initially, work with the city of Porto Alegre / RS, Brazil, the five largest malls here. The stores will create promotions for our customers, sharing to friends who have been indicated by facebook, and also for those that are researching the purchase of these products. I ask you to analyze how to build this system: thinking about the stock of stores, the control of prices, usability of the system in sync with the facebook and gamification to generate medals for consumers. With this information, please request confidentiality and, above all, send me a budget (full price of this creation) to develop this product. Rodrigo Cunha.