I think SharePoint Foundation + SharePoint Designer (free products for anyone with a Windows Server license) provides most of the functionality that a simple application developer might need - Lists (similar to SQL tables), abillity to host simple client
side code (js/xap/swf) and also ability to write ASP .net (through a very simple setting change) code. SP Designer is way advanced in terms of design and coding experience. How do you pitch your product with SharePoint already in marketplace (and remember
SP has a huge deployment/user base/dev & power user community).