Its free!! And, ad-free forever too. And version 1.2 just submitted to apple. V1.2 is added with a new function "Area QuikSplash".. to define sloppily the area your want to splash a color.. and iQuikSplash will do the rest! Sit back and enjoy! CLICK LINK TO GET IT! iTunes Link
If you like this app, check out my other paid app, AppliFX, currently at v1.2. It also sports this filter, plus many other VERY UNIQUE filters like Hue Splash, Sakura, Autumn, Snowy, etc.