I've got a Canon S100 digital camera (the original Digital Elph). It uses proprietary Canon lithium ion batteries. After years of use, the batteries are on their last legs. I've been looking for 3rd-party replacements to save on cost, but the price differences seem to be quite wild with it ranging between $10 to $40 USD (I'm Canadian, eh).

I don't want to spend a lot of money on batteries, but on the other hand, I do want a battery that will hold a charge. Anybody know anything about aftermarket batteries for Digital cameras? Brands to be wary of. Brands that haev a good rep?