SE stuff sometimes goes on sale but the drops aren't that huge, I think Chaos Rings 2 went down to 12 from 18 so don't expect dollar pricing or anything. Dimensions is all-IAP pricing too so that might make it less likely to drop.
I have mixed feelings on Dimensions. Even for SE, you can get very high-quality titles like TWEWY and Chaos Rings for much less than Dimensions. The game is also poorly optimized for the iPhone, just using healing spells in the menu takes way too many steps than it should, or having to scroll down to select all of your party members in battle. Still, the gameplay itself is pretty solid and it more or less gives the fans exactly what they want.