The guys who work on it do an incredible job, so I don't mind paying for the quite reasonable indie license to help them out. If I was to do it myself, I would

The guys who work on it do an incredible job, so I don't mind paying for the quite reasonable indie license to help them out. If I was to do it myself, I would probably end up writing something similar, but not as good and with more bugs. I work pretty much exclusively with startups so Windows licensing is covered by Bizspark. Also, as has been mentioned, it is open source.