This is going to sounds like crazy advice, but having worked on many side projects in my life the last thing that's going to let you down is your skills. What you really need is time. Let's say it takes you 400 hours to build your project -- in those 400 hours, you will build up enough skills to get you started (not nearly enough to be good at it, but good enough).

So you need to work consistently 1-2 hours a day on your side project. It really doesn't matter what you do. If you manage to get those 1-2 hours in, you will muddle through and accomplish something. If your goal is to make a side project and bring in a non-zero amount of money, this is achievable. Learn whatever you learn on that project and then do it again.

Personally, I would spend exactly $0 on your task because, like I said, the thing that will kill you in the end is likely to be time commitment. If you spend money, you will be out the money and your time. So start with time and see where it takes you.

As others have said, no need to get fancy. Just build the simplest thing that will get you started, using the simplest tools you can find.