For your budget I will second the ER6i recommendation. It's clean & lean sound is good for your monitoring purpose.

Get the JVC Marshmallows (some $20) for exercise.

Beyerdynamic DT770

Well the UM1 supposedly favors the low end, while the Etys and UEs favor the highs. The bass is definitely there on my er6i, it's just really tight and accurate. I also much prefer the design of the er6i to the super.fi, since they're really tiny and fit rather deep in the ear canal, so you never really have to adjust them once they're in. I'm pleased with mine and I think you'd like them too!

Edit: Comfort is a very subjective thing, but I'm amazed by how comfortable the er6i is to me, even using the triple-flanges. I use them at my factory job during 10 hour shifts, with small breaks every couple hours, and never have any (ear) fatigue. (Other fatigue, yes)

Beyerdynamic DT770

Beyerdynamic DT770

I've never had an ER6, but I know some people wrap the cord of the ER4 around their ears. I do it with the im716 which has a similar form factor as the ER4. It was a little awkward at first, but I got used to it fast. I know the ER6 is smaller, so it may be even more awkward.

One of things you'll need to keep in mind is recorded music is much compressed. The signal coming from a live uncompressed drumset whether electronic or acoustic is going to be taxing on any IEM not generally intended for this type of monitoring. The bass range takes the most beating and you may find many IEMS not up to the task before breakup or simply not provide the kind of low-end some drummers want/need. Many drummers will use a buttkicker mounted to their throne to simulate the low frequency effect on the body you can't get from IEM's alone. I think you will be unhappy unless you spend a few extra dollars on getting a robust IEM for this type of use. By the time you figure how much a regular monitor/amp/eq/ cost the investment in a good IEM is money well spent. I think Funk-O-Meters post dead on and am thinking about moving to Livewires from the Shure E5 and Westone UM2 I presently use.