My mind pops out sony mdr-1r (STylish!), DT770 pro, and several others.
However, do you have any amp/dac?

Sony MDR-1r: Stylish, Comfort, Isolate moderately, SQ for POP (Slightly rolled off treble).
DT 770: V-shaped. Slightly recessed mids, emphasized bass. Tried pairing with Dacport. Result is sweet spot for pop.
AKG K550: Treble may be harmful. Overall pretty nice sounding. Improved version of SRH840.

Amp/DAC recommended:
Fiio E17: Basic DAC/Amp. Value for Money. With Bass Boost feature.
Centrance DACPORT: Great DAC. Needs laptop to draw USB power. Powerful.

Good bass IEMs:
Vsonic Gr02 BE.
Shure SE 215 SE (if you like plenty of bass).
JVC always have peculiar treble. If you like it that's good.
Denon C100: Bass with above average stage width.

Please state your gears, music preference, previous or current IEM, what quality in the IEM you wish to have, etc. It'd be more accurate that way

what purpose? using which player? in what environment?

Actually DT231 is quite comfortable with the cushion pad. However, not all ears work, like mine not fit.
SQ wise you can say it's one of the best in that price. Value buy. Soundstage is very wide. Suitable for casual listening with not so strong bass. Easy going signature.

Had it myself. Still think it's quite a haul.

If not, you can look at Audio Technica AD series. Super wide cushion for comfort. Or ATH Pro5 Mk2 for monitoring purpose.

Or just up budget go for Goldring DR150, stop there and find peace with all your music.

Grado SR60i
Sennheiser HD202
Sennheiser HD429
Audio-Technica ATH-M35
Beyerdynamic DT231pro

Grado OUT.
HD429 OUT.
Open can disqualified in bus/plane.

Senn signature = BASS
AT Signature = Treble.
Beyer 231 = balanced.

Isolation wise = all are not optimal.

Extra suggestion. ATH Pro5Mk2.
Fischer Audio FA series also can.

punch? in a crowded or potentially noisy place? really need headphones ar? Can go for earphones? Because bass without isolation is almost nonexistence. IEM can better isolate noise.
You don't wanna turn the volume too loud because it could damage your ears.

BTW, budget?

SOund wave is the movement of air. More air normally allows more bass (if the design allows). However, it depends on how they tune the headphones also.

I mean, In Ear Monitor (IEM) earphones are better at bass in louder environment due to isolation, which means the bass won't be overpowered by the noisy environment before reaching your ears.

IEM with bass at such price, i normally recommends Shure SE215.

Headphones? Cheaper ones? How about:
Marshall Major,
Shure SRH550 (very tight clamping)

A modest entry level kit.
A value buy.
However, honestly i must warn u of Audio Technica's Bass.
It is not powerful.
It doesn't slam.

Unless...

You EQ it, or you buy external amp with bass boost option.

But...

The sound, for that price, is considered Quality. Clean.

Honestly speaking, my basslust until today cannot be really quenched, because while hard hitting bass is nice, i also prefer balanced sound.

Sennheiser closed cans good bass > Portable headphones like HD25ii, Amperior, Momentum and the likes.

Frankly, I have less experience with gears produced by them. For gaming, in-ear is kinda bad choice from my experience due to the pressure keep mounting inside, as well as when compared to headphones, it has smaller staging, which could be less ideal for the in-the-game feel. What about portable headphones? Something like Beyerdynamic DT231 pro? Does quite well on gaming the last time I have it. Or probably the HD2xx series Sennheiser? As long as it is portable headphones, it can greatly enhance your gaming experience while keeping it portable, as well as not sacrificing sound quality.


Bass lust eh? Sennheisers cheaper series not bad. Ample bass to satisfy your craving!

Frankly, if you are to satisfy his wish to have a Beats for RM500 it's hard to get anything decent in terms of Sound Quality. However, to balance the scale, he might just want the Aesthetics/Brand?

There are a lot of headphones/earphones out there which could match with Beats in terms of Sound Quality (not looks). The point being, would he still be satisfied of owning something which may look inferior? If he's really into Sound, then we can talk!

Sennheiser does have quite a lot of cheaper earphones/headphones which boast ample bass. In terms of value, I'd pick its portable headphones as it does better compared to in-ears at that price bracket.

Perhaps you could have a look at Beyerdynamic Xp series? There are 3 kinds of Sound to choose from. The looks ain't that bad, and what's more, with that budget, you can get a few more things aside from the earphones itself.

Other than that, Shure SE215 (Limited Edition) is the new-kind-on-the-block. They look professional, sure your friend could feel good with it. The sound? Sufficient bass to handle most tracks at that price.

Congrats!

What about Shure SE215? If you can get a good deal or 2nd hand.