This might be a stupid thread for the experts out there.
I got my Shure e5 for £80, the same as some Sony MDR-XB500 are going for new.
I've recently purchased Sony MDR-XB500 and compared them to my lovely Shure e5.
Perhaps obviously the Shure e5 beat the Sony at every department.
The highs are full and precise compared with the tinnitus aggravating Sony.
The mids actually exist not just as thin upsetting interpretations.
The Bass, the bass, is just as good if not better than the Sony.
The only point where the Sony exceeds the Shure e5 is the physical vibrating of the headphones against the head. Even tho I'm sure with amplification (not just an ipad and iphone 4) the Shure would equally rattle your lugs (Scottish for ears).
Whilst they may appear as complete opposites in terms of price and sound I say buy Shure e5 second hand, you will not miss a thing. In fact, you will only gain a high fidelity world, with ears rattled suitably.