I just want to point out that, E2c(SE110?) uses dynamic speaker unit. It was good when it was first released, but now you can find better (and cheaper) dynamic canalphones in the market, such as CrossRoads MylarOne X3/XB. E3c and above uses Balanced Armature speaker which greatly improve on detail (check
this out).
Now a day you can get a relatively cheap IEM such as Etymotic ER6i or Ultimate Ears Super.Fi 3 studio for $60~100 (both are great entry class B.A. IEM). For $150, you might be able to get Future Sonic Atrio M5 (best dynamic IEM in the market) or a pair of Ultimate Ears Super.Fi 5 pro if you search around.