To address this problem, you need to establish some buying criteria. These may include price range, size considerations and appearance. This last is especially important because the very word jewellery derives from the French word for joy - and the source of the joy is the brightness and visual stimulation afforded by the jewellery, not the number of Newtons it exerts on a piece of iron in close proximity.
The reason for this is that you wear the bracelet long-term and so it is the long-term effect that matters. Even with medicine, where you want a powerful effect to kick in quickly, you wouldn't necessarily want a high dose, if only because a high dose can sometimes be too high. Now I am not saying that you can overdose on magnets, because of course you can't, unless you happen to be carrying a five-ton super magnet on your person - in which case you'll probably give yourself a hernia and then you'll need a magnetic wrap of some kind! But I am suggesting that you shouldn't dwell too much on the magnetic strength of the bracelet.
Pay attention instead to the cry of your heart and the gleam in your eye. If it looks nice, then buy it.