I don't have my business off the ground yet but I've calculated that towards the beginning I'd need to make $43.50 per user per year ($3.65 per user per month) to break even, including my own cost of living.
Uh... guys, aren't you forgetting the number of users you have?
1 user x $100k
10 users x 10k
100 users x 1k
1,000 users x $100
10,000 users x $10
That's true - there are costs incurred that scale with the number of users you have and costs that don't. I guess the real way to answer this question is with a graph.