If you have a bent spring, it is better to replace it then try and have it re-arched. Once bent, the metal will be weaker in that point for the life of the spring and probably bend in the same spot down the road. Not only that, but bending it back will further weaken the spring, making it more likely to break.
For a new main spring, give Hawk Suzuki a call. They usually have left over spring parts, I have gotten a couple second leafs from them to use for an add-a-leaf for my front RUF setup.