Answer: No, save your money.
A recent meta-analysis from the Canadian Medical Association Journal concluded static magnets (commonly found in bracelets) do not reduce pain such as arthritis or fibromyalgia.
Magnets produce energy in the form of magnetic fields. The magnetic field is generated by the spin of electrons within the material itself. According to one proposed mechanism, pain receptors have a lower threshold potential, and magnetic fields decrease neuronal depolarization by shifting the membrane resting potential. Another theory advocates that magnetic fields encourage an increase in blood flow through the skin and the muscular tissues, which reduces the pain.