Looking for a pair 100$ IEMs

Would Etymotic MC5 / ER-6i / HifiMan RE0 fit your bill?

I'm based in Australia, so i don't know of any shops in London that may stock them. I only know of Head-Direct.com which is the official supplier anyhow.

Etymotic also have particular IEMs with an in-line remote and mic if that's what you want. I can't remember which though. 

I would suggest that you look at the Etymotic mc 5 or mc-3 models.  Either of these will fit your price point, the sound quality is the same, and you pay only for the the control and microphone functionality when you step up to the mc-3.  You will truly love the extended range at both end of the spectrum, and build quality is superb.  Both of these models also come with excellent noise isolation and an custom fit ear mold upgrade option. 

If it helps, I wrote a comparison review between the MC3 and the RE0.

General take away is, the MC3 is a great package considering the price, build quality and sheer degree of noise isolation they offer. The microphone controls are awesome to use on the iPhone, namely because (and I didn't even realise you could do this) you can control music play back through the microphone - so you never need to take your iPhone out of your pocket unless you don't want to look crazy talking to your self. ie: You can literally command your iPhone to "Play artist The Decemberists" and it will!!

They have a pretty etched, slightly dry sound, so I wouldn't recommend them if you are particularly sensitive to sibilance, or if you want a very tactile feeling of bass. Other then that they are very transparent and a nice package vs the RE0's for portable use.

are you sure you don't want to try a full-sized can from your ipod? such as the straight wire m50s.

portable use with the M50 straight cable..you kidding me? The coiled cable is long enough let alone a straight one

For isolation I'm tempted to recommend the MC5 over the RE0/RE-ZERO even though I prefer the sound of the H-Ds.

Also consider the RE-ZERO if there are any left. The RE0 with improved appearance and build quality and with smoother mids and less pronounced treble. Loved mine for three months odd now.

"portable use with the M50 straight cable..you kidding me? The coiled cable is long enough let alone a straight one"
 

hey who actually goes around with headphones anyways? when people do, i don't think they care about the grado's wire length or the monster pro's length. i was just telling him to try a pair of closed cans if he never has.