It's probably cheaper in the long run and for reliability to replace the radiator. On a 2WD it's a 2.7 hour labor operation to replace the radiator. I would say $200 to $300 for a radiator $25 for antifreeze/coolant.
Depends on how bad the leak is. Does there appear to be a lot of corrosion around the edges of the radiator or near the leak area? Really it can go either way. Your best bet is to locate a radiator shop near you and take it in. They will be able to be more specific.