I had the idea to build something very similar, but hoped to find a pre-existing solution. When I found idonethis, I found the cost prohibitive, so I built it myself.

It took me about a week, so that's fair, but that's to rebuild not just the core functionality, but also the multi-tenant SaaS part.

I have a 50 person team. So, I would've paid $250/mo, or $3k/year. So, I really invested $2k to develop my own version, which also has the potential to make money if people prefer paying $15 for a team of unlimited users.

So, no, I didn't find that a waste of time. Plus, I learned some new things along the way, and can fine tune the app as I see fit.

This is the risk of building a business around simple, contained functionality. They're easy to clone, and you better get the execution and pricing right, and figure out how to expand on the concept, or you'll be commoditized quickly.