$100 max budget? Want massive bass?
The
Hippo VB bar none. $89 shipped (with free DAC) from jaben.net
If you want to up your budget to something ridiculous, Sennheiser IE8 is apparently bass-heavy. Though I've never heard them myself, a friend has them and he actually dislikes that the IE8s pump out sooo much bass.
Also, having owned the CX300ii for a while, I think it kinda sucks. The amount of bass it puts out does offset its lack of clarity compared to similarly priced IEMs (MeE M6

). It's not as durable as the M6 either.