Traveling advice website

This is my friend's idea and I was just wondering how much it would cost. So her idea is to create a travel app that focuses on getting local knowledge to tourists. Think of "hidden gems" in a city rather than the typical tourist stuff. For example, local knowledge on the best restaurants, clubs, events, dances, live music, underground rap places, good workout areas, best places to surf, water hot springs, etc... Her idea is that it would have a snapchat like feature where you go to a city and "locals" are identified on the map based off if they have been living in the same city for 6 months. Each local would have an "avatar" to showcase the knowledge they have. If they know good places to drink, then it would be avatar with a beer mug, someone with good knowledge of the local surf places would be dressed like a surfer, you get the idea. Then, someone coming to a city could click on the avatar and ask him/her questions to get the local scoop. There would be a limit of 1 question per week, for 140 characters or less. If the tourist wants to ask more, they would have to upgrade to a premium version. This would cost $7 per month, $5 per month for 3 months, or $4 per month for 6 months. Additionally, we would have advertisements on our website to generate more revenue. Lastly, we would pay our locals to answer questions and have a feedback system. So they get $0.10 per question they answer. IF the rating goes up, so does their pay. The tourist asking them will rate and that rating will be public knowledge. Plus, we would have a google and facebook sign in to help save money and time with new members. So that's the wind up and the pitch. She doesn't necessarily have a time limit, but she is looking for quality. 1 year maximum.