Domains cost $15 a year. With due respect, if my business lived or died on $15 a year, I would probably close shop.
Yay! "Due Respect"! Wild thing, you make my heart sing. Let's try again, shall we?
I'm not asking for business advice. Let's focus on the question, which seems like a perfectly reasonable question for this forum. I'll reword:
For no reason whatsoever, you know, just for the sake of curiosity, I'd like to know about monetized domain parking. Has anybody done it? Is it worth the bother? What scale of monthly income are we talking about? $0.10, $1, $10, $100, $1000? I have no idea if this totally worthless or a surprisingly lucrative way to make money without doing anything at all. My suspicion is that it's practically worthless, but I'd be happy to learn otherwise.