This is an excellent price, almost free, for a very fun puzzle game. It looks simple but it is hard to master, especially on later levels.
Very good value for money. Can be played in short bursts if you have the self discipline - it can be addictive. ;-)
Enjoy!
I see $0.49 USD on Steam, and I believe that is the lowest possible price as well. I sort of remember an announcement about it yonks ago.