Sodium Percarbonate is a good one - if you have oxyclean or any variant thereof in SA it's essentially the main ingredient. A hot water soak with the stuff will take care of most bottles, just make sure to give them a rinse or two afterwards.
Some labels, such as vinyl labels or painted-on labels, and some sticker glue will still give you trouble. In that case, you can toss them, give them the hot water and steel wool treatment, or use them with the original labels.
As @tgolanos said, percarbonate will clean the insides nicely as well. Technically it will also sanitize them since it breaks down to sodium carbonate (a natural detergent) and hydrogen peroxide (a sanitizer) in water, but once you've rinsed off the residue of the sodium carbonate you probably want to do another sanitizing step before bottling.
If you can't get percarbonate, a simple hot water soak will take care of a lot of stuff, even better with washing soda (that very same sodium carbonate) or baking soda added.
Not so relevant to labels, but the most important step when it comes to cleaning bottles for reuse is to rinse them out relatively soon after drinking. If you rinse all the crap out of the bottle before anything dries on the glass and make sure that nothing else gets in (i.e. store them upside down or with something covering the mouth), you'll just need a quick spritz of sanitizer before bottling and you're in the clear.
edit: also, ten dollarydoos for a kilogram? Dang! It can be hard to track stuff down here in China, but when you buy directly from the source, it sure is a damn sight cheaper! I buy kilos for about 1/3 that price or could get a 25 kilo sack for less than half the price per kilo of my current price if I needed to use that much...