NielDLR
the language reader market is currently a bit saturated with open-source and paid alternatives.
However, I looked at your site. I'm a linguist with some expertise in web development (http://hanzicraft.com, http://polyglotlink.com and some other sites under my belt).
I really like the idea of a quick importing using a bookmarklet. My main language that I'm learning is Chinese as this market has MANY options (http://3000hanzi.com, http://chineselevel.com, http://lingq.com, http://duable.com, LWT). It's hard to choose. I particularly enjoy ChineseLevel mainly because I know the developer, so I'm biased.
In any case, I think it's possible to get at least some income with your startup. To make it a full-time job is something else and depends on your needs. Because the language reader market is saturated, you'll have to set yourself apart from open source and paid alternatives. At the moment I'm not exactly sure what that is, but I'll be trying your site to learn a bit of Spanish and French (I'm a language learning addict).
I can help you with some more advice and testing if you want. I can also give you some linguistic advice if it comes up. Send me an email: [email protected]