I've always loved the octave in the line 6 pedals, so I sure you could pick up a line 6 m5 second hand for that sort of money and it gives you loads of other effects as well. If you after a standalone octave though I did like the ebs one alot but it depends what sort of octave sound you want. An oc2 style octave is for me a bit more 'synthy' and wasnt my thing, so I stuck with the more 'natural' sounding ones.