Why do you want an original Canon battery? Get on eBay and search for NB-2L
battery and buy from one of their top vendors (they are marked as such). I
never buy Canon batteries as additional or replacement batteries. Generally
the big box stores had generic batteries for about 2/3 of what a Canon
batter will cost you or on eBay you can buy one for about 1/5 the Canon
price. I get two to three years service on the cheaper generic batteries.
Check the comments on Amazon for any of the NB-2L batteries (including the
Canon brand products listed there -- many comments there about "i'll never
buy a non-Canon battery *or a Canon-label one from other than a certified
Canon dealer*" comments).
It's not the years of service so much as the hours of charge they will
provide. Taking all the comments I've read, non-Canon batteries and the
counterfeit Canon batteries will not stack up to Canon label ones.
This isn't to say that the batteries you buy are not a good deal for you.
Each has to weigh his needs and the costs.
Going to the Himalayas. Need the longest-charge power I can get. In my
research, this is Canon-brand NB-2L's from a reliable dealer.