Backstory: We always buy things from Amazon, prime shipping is super addicting and we've come to expect all packages to get delivered in two days or less. The other night a friend was talking about how he bought an $18 bike from prime day for his daughter. We then went on to discuss how prices fluctuate on amazon and you could score some good deals if you averaged out the price of an item and auto purchased when it dipped below a significant percent below average.
The Idea: A site that lets you pick a niche in amazon and anytime an item's price dips below a set average it automatically buys or alerts you.
Deep Dive: Thanks to Gary Vaynerchuk eBay/garage selling is a fad again. I even saw a medium post by Ryan Bates on this! https://medium.com/@itsryanbates/how-to-hustle-on-ebay-74a116fed569. I was a little sad to see this Ryan Bates was not this Ryan Bates but it's still interesting to see people posting about ebay reselling. Initially you could build this app for yourself, prove that it works by reselling stuff on ebay using your "unique algorithm." You could hype it up and sell a limited set of licenses at a premium. You wouldn't get "Uber" rich off this idea but you would make some money in the process and build a small community around reselling. This would be more of a passion project and you would be riding the wave of reselling but it could be fun and unique!
Validation: This is the bike my friend purchased: