Multipurpose (Music + Gaming) + Closed + Mic + Budget RM300 headphone:

[+] Plantronics GameCom 377 (RM 199)
[+] Sony Official Wireless Stereo Headset 7.1 (RM320)
[+] Creative Sound Blaster Arena Surround USB Gaming Headset (RM 339)
[+] Logitech G35 7.1 (RM 360)
Multipurpose (Music + Movie) + Open/Closed + Budget RM200 headphone:

[+] Audio-Technica ATH-T200 (RM89) / T500 (RM 219) - Closed
[+] Audio-Technica ATH-AD300 (RM 269) - Open

Logitech G35 net weight : 370g (not really heavy...)
Multipurpose (games, music, movies) + Budget RM100 headphones:

[+] Audio-Technica ATH-T200
[+] Sennheiser HD201
Sport + Canalphones + Budget RM100 earphones:

[+] Sony MDR-AS20J

try jaben network SS15 subang jaya

Listening to music WHILE drumming?
You mean you need a monitor to hear your drum being played into the mix while you're drumming, like a drum cover?
Well......you need something that emphasizes bass a bit, something to emphasize that drum a little. I was going to recommend the FS Atroi, but that's RM600.

In my experience, the Sony MDR-EX300 did actually sound pretty nice and very comfortable. You need music to play for it to isolate though because it is vented and sound leaks in. Clear enough for music and the bass, although has a bump in the mid-bass quite a bit, still is great for drums. Not the most detailed sounding for its price (has got clear detail but you need to have your mind and ears work to hear them), but definitely fun sounding. That's the older EX300. The newer EX310 may be better. That's my best recommendation FROM MY EXPERIENCE (I'm not yelling but emphasizing    ). They have a J-cord design though so you might not like that, but it was easy for me back then to get the cable out of the way so it wouldn't rub on to my shirt much to minimise microphonic rubbing noises.

The other one, but I don't have any experience of, is the DUNU Trident. It was recommended to me when I was looking for a bass IEM. I chose the Atrio instead because I had the budget for it. The Trident is described as being warm, comfortable and has great bass for the price offered. You can refer to a seller here for more info, and maybe he has some other IEM in his store that you may want.

Also others I don't have experience with, but was told that it has a killer bass, the Fischer Audio Eterna and Consonance. They are maybe very coloured though. The more neutral is the Paradigm but with less bass. You can audition them at Jaben I think, or the other seller here who carries Fischer Audio products (sorry I forgot).

[+] Audio-Technica ATH-CKM300 / ATH-CKM500
[+] Sony XBA-1
Clarity + Comfortable + Good isolation + Budget RM2XX IEM:

[+] Audio-Technica ATH-CK313M (clarity) + Comply TX-400 (for better comfort + isolation + fit)
[+] Audio-Technica ATH-CKS55 (solid bass) + Comply TX-400 (for better comfort + isolation + fit)
Microphone for PC/Laptop - Zalman ZM-MIC1 (clip on mic for gaming and skype)

Clarity + Bass + Budget RM 250 headphones:

[+] Audio-Technica ATH-TAD300
[+] Sony MDR-MA100

I never did have a chance to try the Eterna. But it is consistently reviewed as being very musical and engaging. Detail isn't what it is for, but it doesn't hide the detail, just presents it in a fun way. No comment on the C260. Take this with a grain of salt. For your criteria of IEM I hadn't had much chance in experiencing a lot of them.

If you want isolation, then the Sony XBA-1 is quite good. Non-vented and with good silicone tips and compact design. A single BA sound sig is very easy listening and good with detail.

Others with good sound isolation I've tried are Hippo Shroom EB (careful not to stick them in too deep  ;P  ), SoundMagic PL50 (with the foam tip or Sony hybrid silicone tips) and.....well those were it basically that were decent.    Both aren't really bass monsters though.

BA, Balanced Armature. It's another speaker technology. Different from a conventional speaker (called dynamic) you see most of the time. The sound sig a single driver BA IEM generally produce is emphasized mids, fast and articulate bass but without much amount, good treble but without having very much energy but good detail nonetheless. Sound may be a little different between manufacturers but that is roughly how a single driver BA IEM typically sound. Can vary greatly with multiple driver (speaker) IEMs with BA. Those super detailed sounding single-BA's are in a different league and certainly out of your budget.

Yeah they're actually pretty good. It does take some practice putting them in, but once you get used to it it's great!

Westone UM1