Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.

AliShark - Usually, you only see those top-selling products, leaving those hidden gems behind. With Alishark, It doesn't have to be a top seller to be spot anymore.

Fetchee - Fetchee is a free price tracking wish list app that works with all online stores worldwide.

Ecomhunt - Ecomhunt allows you to easily find products that are already proven to sell or how we like to call them Winning products! - in only a few clicks - it's time to stop guessing, start selling!

Keepa - Price history charts and the option to be alerted on price drops for all Amazon sites.

DropshipScan - Product Research For Dropshipping - Find a winning product for your store!