To create an app like Amazon, you will need to work with the best ecommerce app development company. I concur. The good news is that you now have a larger market to claim and generate revenue from. The cost of developing a multi-vendor app can range between 20,000 and 80,000 US dollars, depending on the wireframes, platforms, and complexity. I would recommend that you consult with an app company and share your ideas. They will give you better budget advice for creating an app like Amazon.