...yes its actually easier with less money as 83 clicks a day is all you need so you aren't competing with high cost keywords which tends to start being unavoid

...yes its actually easier with less money as 83 clicks a day is all you need so you aren't competing with high cost keywords which tends to start being unavoidable somewhere past 100+ clicks/day. And yes, I've done this with $500/month as the spend. If you go through my comment history you'll notice I used to work entirely with small businesses as a contractor which I've mentioned at least a couple times I believe. I wouldn't use up-to-date hypotheticals from my current job given its a scale almost no one on HN would operate at. :/ I'm not really sure what your conviction this isn't possible comes from? Obviously, $50/month/sale is not going to work out for a book that sells for $10 but that is a different problem.