Over the past couple of months I have been compiling a list of the costs of different webapps into an Excel Spreadsheet to get some insight into what other people charge.
My conclusion is that utility based applications e.g Basecamp average around $3500 per year for an Enterprise account. Where as Revenue Driving applications e.g. Seomoz, average around $8000 per year for an Enterprise account
My conclusion from this analysis is that if I am going to build a Muse I should certainly target revenue drivers rather than utility based apps.
I have posted the spreadsheet on Google docs, so please have a look and add any that you think would be informative.