I'm sorry to hear that. There is a lot of activity on the KDP forum on this topic (four or five threads, the last time I checked). It's been a couple days, but there were some people saying their prices were back to normal. The one I had that was off reverted to normal after a day or two. I take this to mean that Amazon is at least trying. Support responses have been mixed, but apparently, most of them acknowledged a problem and said it was being worked on.
Some people on the KDP forum were arguing that it might take a long time to find the source of the glitch because of how complex the code must be. I'm no programmer, but I couldn't help wondering if there isn't some simple routine whereby product pages communicate with some kind of database (or for self-published books, perhaps KDP dashboard data) to check prices. I guess there's no way to know.
I don't know if this is related, a separate glitch, or a decision to change the system on Amazon's part, but I notice it's no longer possible to just change prices (which I did easily only a few days ago). Now, there's an error message that tells me there's a problem requiring attention if I try to submit new prices, and I have to go back and resubmit all the earlier pages in order to make a price change. Sigh!