Seriously, if you're going to do it this way, put magnets in the "shoulder sockets" and back and small magnetic pieces of metal in the arms and back pack. Rare earth magnets don't come cheap, and they are strong enough. Half the price.Dude,
Check out the 1/8 inch rare earth magnets and put one in the end of the arm with another one in the body. Make dure they attract rather than repel.