As Konrad said once you are done with basic features which will take you a couple of months, you will have to invest a lot more time adding all the small features and tweaking functionalities and market is also changing so you will want to follow trends.
You are motivated which is good, so keep going!
Shoot me an email to
[email protected] and I'll give you a free copy of ours script. We developed it but never actually started promoting it. It took some time developing it, but might be a good start for you