I'd like to add something with regard to open source software.

1. community editions may be free and will get you started but once you get beyond a certain point you will want the commercial editions which are definitely NOT free.

2. If you need support then this is NOT free. In fact "professional services" can be very expensive.

3. If your open source choice is not something you would or could contribute something to then what is the benefit. I couldn't contribute to MySQL or PostGres code. I might add something to Hibernate or Solr at a push.

4. Open source projects seem to attract the masses. It used to be that only the big players could afford an MPP appliance and only they had "big data". Now that many people say they have "big data" projects such as Hadoop start to come to the fore.

5. Open source projects with some overriding governance seem to be the ones that survive. The rest fragments and die.

6. Very few people can afford to work for free. Businesses chasing free software from companies without a viable business plan are going to be left holding an ugly baby.