Transparent bumped material for mobile

I want to use bump-mapped quads for sprites in a mobile game, my thinking being these will be a lot cheaper and faster to render than full 3D, and higher quality without aliasing. However, Unity’s selection of mobile shaders doesn’t support this, and there’s a warning when using the standard material (Transparent - Bumped Specular) could be too taxing.

Is there any way to determine what a material ‘costs’ and what mobile hardware will be able to accommodate it comfortably beyond trial and error?

you can start browsing the forum and you’ll find a SHADER section?

Thanks. That’s full of useful info.