Nice work! I also built something very similar called Page.REST (Show HN thread: https://news.ycombinator.com/item?id=15189099)
Page.REST supports extracting contents using CSS selectors. oEmbed and OpenGraph tags. Also, do you plan to support extracting from client-side rendered pages (a la React)?
BTW, I'm interested how you decided the pricing? I went with a $5 one time fee as most people use such tools for ad-hoc purposes.
General question to readers: What do you think of the Schema.org format? Is it easy to consume? (from a language library perspective)