Hello ,I have seen your requirment and I have ready app like Marketplace where people who wants to sell some specific products (products should be the ones offered in the store, like specific postage stamps) and those who wants to buy can pick a vendor that is closer or that has the best price or the best rate. geolocation with credit card payment
I have developed it with backed I will show you full apk and admin panel to test,
I will make android ios and control panel Website
I can share apk and admin on chat here not able to attach ,
Looking forward to your response,
Thanks
Technorizen