What are you vendor lock-in war stories?

The typical argument to choose a proprietary solution is this: "Focus on your delivering value to your customers now and you will see the rest later."

While I think this is a very valid argument, I am curious if you had some worst-case scenarios or "war stories" to share about vendor lock-in that had a really bad impact on the business, like a database vendor that drastically hikes its prices or a critical vendor that simply shuts down, etc.