check out Zero Audio Carbo Tenore. They go for 45USD, single dynamic drivers and make a great backup pair. I put them in and often ask myself why I spent so much on gear when these get you 80% of the way there. They pick up well with a good source, and need a little bit of power to get going. They have a "W" shape Japanese tuning. Nice sub bass, scooped out midbass, a peak at the mid-high midrange, another scoop out of the sibilance region, then a nice treble.