This same, exact crack just happened to me!
I placed the car with the radiator higher than the engine, made sure the coolant level was below the crack, hit it with hairdryer for a while, sanded the area, took a Dremel tool and ground about a quarter-inch groove along the entire length of the crack (this probably has the same intended effect as drilling a hole through the radiator as per arondale's suggestion), then took a small piece of very tough, flexible & clear plastic, sanded it and then made the repair with JB Weld. One "coat" under the patch and one coat (application?) over the patch. Put a shop light on it overnight, then let it dry for 48 hours.
I have had very good luck with JB Weld in quite a few instances.
If the surfaces are properly prep'ed (prepped?) the repair area is often stronger than the original material.
We'll see, I guess!
Cheers!
One question, though: what DOES a radiator co$t?