Squids Wild West, $1.99 --> 99 cents.
First sale since release. If you're a slingshot physics fan looking for a neat challenge, or a different spin on the genre, then check out this RTS-slingshot physics mash-up. It's an absolute steal at 99 cents imho! A really fun game, worth every penny, and a good challenge to boot.
Note that IAP is not required at all to complete this game. There's very little-to-no grinding. It's simply there to reward the devs for providing a great experience, if you so choose.