Ok folks, I finally got the spare batteries...
Bought 3 3rd party batteries from Orient Photo at $35 each. A 3rd party external battery charger at $25. I can't remember the brand name of the 3rd party battery but they have only one kind and it comes in a small paper box with light blue and white markings. The battery is rated at 5800 mAh which sounds a bit dodgy cos the power rating on the Sony original is only 1080 mAh? Also the 3rd party battery is very much lighter than the original - to which the Orient Photo chap said that the quality of the capacitors in the original are much better and therefore are heavier. Warranty is 1 year with Orient Photo with receipt to be kept. I charged the batteries and they each took quite a while to charge. Whether that means the charger is slow or the battery capacity is high is debatable. I have not field tested the batteries yet but I shall in a few week's time... Let's see how many shots each battery gives... My feeling is that the quality will vary quite a bit between batteries. By the way, these batteries are all made in Japan...
As for the charger, it is very light but it is not just a custom charger for the NP-50... that's a pity as it has another bay to charge another type of battery... that makes the charger larger than it should be... the whole device is very light and the transformer is very small and compact. So overall for $25 it's quite a good buy I think. There is an LED light that glows green when there are no batteries plugged in to charge. An empty battery will cause the light to go red and then when it's charged it turns green. So pretty straightforward there. No additional plugs or switches. The unfortunate thing is that the transformer is not integrated into the charger base but is a separate box on the power cord. The power cord is detachable though. So you can replace the transformer easily if you fry it when travelling overseas (very possible for countries with frequent brownouts)...
So for anyone looking for 3rd party batteries and external chargers, you can try Orient Photo. Unfortunately they do not have a charger that can charge two of the batteries at one go... anyone has lobang as to where to buy a double charger in Singapore, do drop a line here... many thanks in advance...
Hope this little feedback helps the bros here...