It may work using an open source model. However you don't really want to invest into non-core business(es). It takes away money, talent and energy that you would better put into doing what you do best.
I've experienced this first hand developing an invoice system(not my core business). I still use it but if I were to do it again I would develop only the functionality that I was missing in the commercial offering and try an integration. Time spent on the none core business is time wasted.