The $300 is a lifetime fee, not annual. The annual fee is just $50. While I'm not a fan of ANY taxes or government "fees", including this one, I don't consider it a "blog tax" like some do.
If you are making money on a website, whether it's through ad clicks, selling links, affiliate referrals, etc. you're running a business. The $50 fee for this is less than the cost of incorporating, and you have to pay taxes on the income you make anyway whether you're considering yourself a business or not.