If you do go with .NET and you are intending on forming a real company, then depending on which country you are in you can get pretty much all of the Microsoft development software for (I think) $100 - payable at the end of 3 years. I don't think this is open to every country, but a pretty cool programme to enrol in if you can. Microsoft Bizspark I think it is called. There are a few other variations as well, for different types of startups.