I picked up Hand Tint Pro. It was $2.99, not sure if that was a sale price, but it was one of the three I don’t own.JixiPix has many of its effects apps on sale for as low as 99 cents. Most of the apps are available for iOS and Android both, but from what I can see, only the iOS apps are on sale. (If any Android users know different, please jump in.)
The list of iOS apps is here -- you'll need to click through on each app to see the current price.
Also, if any of you Android folks know of app sales going on, please post them in this thread!