For the same apertures, the 50/1.8 ii is a tiny bit sharper, and that's a lot cheaper. Add a full 68mm set of Kenko extension tubes and the 50/1.8 can get to 1.35x magnification, for cheaper than the 50/2.5 macro.
But then, the niftyfifty bokeh is nice and pentagonal, and it's not the sturdiest made lens (and changing to add in extension tubes can get tedious)
Pretty much all 50mm lenses are going to be cheap compared to other lengths, they're called 'normal' for a reason...