I set the price of Blot at whatever I would be comfortable paying myself. When I started Blot, it cost $1 a month. I’ve improved Blot since then and now Blot costs $4 a month. I feel that’s still a fair price since I provide web hosting and personal support.
I’m sure I could get away with charging more but I won’t. However, I’m interested in having Blot in the hands of more people, even if it means generating less revenue.