As a serial maker, developer & dad of 2 children, I never have enough time to work on my projects. These days, I'm focusing most of my spare time on improving React Milkshake (www.reactmilkshake.com) and MakerMove (www.makermove.com), so there just wasn't enough time left to continue with FlowReads. That's why I decided to put it on sites like SideProjectors and try to sell it.
Luckily, there were some people who were interested in taking over the project, so I ended up selling it for $2500.
I know this is not big money, but here's why I'm happy with it:
I had fun building the project
I learned a lot
It didn't look like the project was gonna make me a lot of money
I wanted to fully focus on other projects
Here are some learnings I got from building and selling this project:
Earning money with Amazon affiliates on books is hard (average earn on a sold book was like $0,80)
Building applications with Firebase saves a lot of time if you need authentication. I'm now mostly working with React, Firebase & Firestore instead of building a complete API myself.
ProductHunt upvotes do not say anything about your business. FlowReads became Product of the Day, but after a couple of days, all the traffic was gone. I think a lot of upvotes can mean that people like your idea, but it's not a validation for a profitable product.
Selling a side project takes more time than expected. (Transferring domains, social accounts, documentation, code, etc.)
$2500 can buy you nice things