3 budget buds that are frequently mentioned here -- b40, me80 and fengru's version of the mx500.
My favorite is the me80, but the mx500 sounds FANTASTIC for $3.61 (mic and a pretty decent cable).
Very interesting to see the B40 as having the most amount of bass & mids from that FR graph. Offhand, I wouldn't have pegged it as being the bass-iest of the three. And apart from everything above the upper mids, the ME80 and EMX500 seems to be pretty much identical based on the graph.
Intriguing...