Andrew Kamphey spent $1009 in one month on newsletter ads to promote Google Sheets. This experiment took place in 2020. He shared the results and lessons in a Twitter thread.
He advertised in 11 newsletters. The least expensive ad was $10 and the most expensive was $300. That was an average of $91.72 per ad.
The sales data for the month was only $400 more than normal. However, he saw days of small sales spikes correlated with a few newsletters. He calculated that 31 sales – or $589 worth – were above the 7 day trailing average.