Buying and Selling - estimate value of items and predict price drops

This will be especially useful when shopping for used items like an iPhone for example, or when trying to sell one. Possible data sources include Ebay, Amazon, Walmart, Mercari, Craigslist.

It would also be useful to use historical price data from sources that record that data like camel camel camel and Honey, so you could use AI to predict potential price drops (very much expected for all electronics like computers, TVs, and smartphones).

The predictive analytics on price drops would obviously be helpful to buyers, but as a seller it would help you stay ahead of those price drops by offering more aggressive discounts/sales.