One of the common arguments for proprietary software is that there is some kind of permanence in having a corporate entity backing the product you have invested in. To counter this I tell the following story. When Java first appeared in the mid-90's I was very eager to learn it and invested in a Java IDE from Symantec called Visual Cafe. It was a good product and won a best tool of the year award , a CNET Excellence award for Internet tools and many other accolades. Things were good and I was learning Java and paying handsomely to keep up with the Visual Cafe updates. Yes, I was thriving in the throes of capitalism and proprietary software ... and then it was gone.
No, Symantec didn't go out of business. They sold the product line to BEA and BEA did nothing with it but put it away - my investment meant nothing (caveat emptor). What remains of my investment is an unsupported product that is out of date and useless. My graduate research mentor used to say, "Don't descend into the well on a frayed rope." In my mind proprietary software is a frayed rope. Buying a software product should mean paying for access to code not a black box (I am reminded of Scott McNealy's question "Would you buy a car with the hood welded shut?"). Then, if the software company goes out of business, at least you have the code to do with as you please (except take it and sell it again). Better yet, go with an open source solution and use the money you saved to invest in a person who will know and understand how the software works or buy support from the people who wrote the software. Then there will never be a time when your software becomes useless due to bankruptcy or pricing. Beware of proprietary software, it is a short term solution with no future. Go with open source - no one can ever take it away from you.