I can't say that I've even seen them here. I have several sets but most are either the normal one or the long on one side style with the ball hex on one end (I particularly like those as you can get to hard to reach places without need to be perpendicular to the nut head to insert the hex key. I believe mine are Proto which if good enough for the offshore oilfields where I used to work, they're good enough for me.
Having said that, we used to use a liquid rubber to dip adjustible spanner handles in to give a nice grip to. I reckon you could use that stuff but it would probably cost you more than it's worth. Most hex keys are kept in a sort of plastic holder that is sized and labeled though, unless it the type that are hung on a ring with swivel hooks that slip over the long end of the hex keys.
I assume that these are what your are looking for:
http://bulletin.accurateshooter.com/200 ... r-freight/
I forgot about the T-handle type of hex keys (all mine are the "L" shaped ones. This one you can order from the US and it's actually two sets, one in SAE the other in Metric. They will ship to Singapore but will have to contact for costs.
http://www.ebay.com/itm/20-Pcs-T-Handle ... 2a27125365