I'm no audiophile but if you want headphones, then i think you should look out for brands like audio-technica, AKG, sennheiser etc.
I suggest audio-technica. If you are a music lover, then heavy bass shouldn't be your cup of tea. Since you are traveling by bus, its essential you cut down on noise as much as possible and as far headphones are concerned, circumaurals are the things to look for.
I used to own a PL50 earlier and recently they died. I narrowed down between Headirect RE0/re232 or NuForce 700.. I bought the nuforce and man are they great Bang for their money. I am a bass lover and the Nuforce completely satisfied my hunger.. Chk it out.
Also check out Beats by Dr. Dre at that budget.. they are supposed to be THE BEST earphones for bass.. Although may not be the best for the kind of music you listen to.