I went ahead and bought a bunch of indie games, picked up Darkchaser, Oxygen Not Included, and UFO50, and also grabbed Cities: Skylines. Got used to the launch prices of some AAA games, buying these discounted low-priced games really doesn’t hurt much.
Get it as soon as you can afford it. As you have already noticed, the price only goes up, and it never goes on sale. The people that made this game know that they made digital crack, and aren’t inclined to spread the addiction.