If it helps, I tried modelling 37signals' revenue a while back. Based on some of their posts and a few guesses I think they've got about 10k paying Basecamp customers, and across all their products will have about $8million in turnover this year.
You can play around with the spreadsheet I created, though I hope to update it soon.
I think it's absolutely easy to see that you can get 5000 users paying $20/month if you provide $20/month of value to your customers! Are you saving them that much per month in other costs, or generating new revenue through your software?
My original blog post is here: http://blog.jedchristiansen.com/2008/02/25/37signals-is-one-...
You can play around with the spreadsheet I created, though I hope to update it soon.
I think it's absolutely easy to see that you can get 5000 users paying $20/month if you provide $20/month of value to your customers! Are you saving them that much per month in other costs, or generating new revenue through your software?