Real marketing efforts can not be measured meagerly by just $300. Most online marketing campaigns run tests of $100/day easily for 30 to 90 days, sometimes even longer to test metrics of what works and what doesn't. Depending on your quality score and your keywords, your CPC won't deliver you a whole lot of traffic with $300. Worse off, the 11 that bought from you is not enough data to really measure what works and what doesn't to improve scalability long term for paid traffic.

On the free marketing, since I have no clue what you did, I will assume you're lacking a lot similarly to your paid traffic attempt.

I am not an expert at these things but if something didn't take off despite your marketing efforts. Your product probably doesn't have a market. e-books might be hot but not the niche balloon business. You should move onto the next e-book. Hopefully it will do better.

If you want someone to just bounce things/ideas off, hit me up, email is in the profile.