Other people have touched on your price and quality/usefulness of the app, so I'll ignore those.
You're conversion rate is around ~0.3%, which actually isn't that horrible for an unoptimized site. Between 0.25% and 0.5% is pretty average for newly launched app.
In terms of marketing and copy, you need to work on your message and audience. Who is going to use this? Probably not techy people who know how to use Photoshop/Illustrator.
Perhaps grandmothers wanting to draw something for their kids? Or kids drawing something for their grandmothers? Either way, neither of those audiences know or care about "jQuery". This is just one example of how you need to optimize your message.
With that said, I wouldn't put time or energy into promoting this further. There are a lot of great drawing/illustration programs, both online and offline, so its a pretty competitive market.