whitehat bots

I was reading a random old thread with suggestions for tools to buy if you had $100 to spare and wanted to grow something. However the thread was 3 years old and things have changed since then. So I wonder, if you had to (hypothetically) start your journey over again, and you had $100 to spare...

So I am in the mood to build a new bot, any suggestions on what to build? and prices to sell it? i work for seo-bots and just need a project to contribute.