The RE0 is not bass heavy.
Are you dead set on the $100 limit or would you spend $125 if it meant something considerably better or $150 if it was really, really good? I'm just curious how firm you are on your price range and what you may be willing to get.
One immediate suggestion would be Phonak Audio's PFE. It isn't much above your $100 limit.
Future Sonics Atrio M5 would be another but around $180 but apparently some of the best bass of any IEM.
There's lots of options really, many of which I've never heard. I've used the PFE and frankly it's remarkably good and priced very well. the Atrio M5 is well known to be quite the bass monster. It is a little pricey though. There are other options too, some expensive, some not so much. An example would be Sleek Audio's SA6, an adjustable earphone where both the bass and treble can be tuned using different filters. It is double your price range though. Just realize these things do exist and despite you wanting to only spend $100, they are there and function quite well. For most people, the budget isn't terribly important, even if they say so. Most folks just want something good but don't really think of head-fi as "worth" several hundred dollars investment and compared to the $5-$10 cheapies in-store, a $100 is quite spendy. I will kind of point out that to get seriously good earphones, you will typically be above the $100 mark and generally between the $100-$200 range for the most part. Some get more expensive. For example, my current earphones are Yuin's OK1 earbuds, I think $225, spendy for just a little set of buds, but at the same time they are very, very good. You sort of have to judge your own worth really. This isn't to say staying sub $100 is bad. It all just depends on what you're looking for, what is required for you to actually get that sound, and how much you really want it.
There are tons and tons of reviews on this site, so dig around some, read, and certain options will pop out at you as better fitting products towards your end goals.
