Glad to hear that you sourced the problem. Swapping a radiator out is a piece of cake. I have seen a few threads on here indicating that the dealer right now seems to be the only option for an oem radiator. Don't let Manny, Moe, and Jack work on your car!
After you get it fixed, just keep an eye on the temps. As long as it stays in the middle and never starts going up to H again, you may not have a problem.
If you need to replace the head and do all of the labor yourself, you'd be looking at say $350 for the casting with valves/springs installed, $54 for headbolts, $100+ head gasket set, and $14 for coolant. Depending on your miles, you might want to change your belt and water pump since you'd be right there during the process. That would be another $100 or so in parts. Again that is worst case scenario and hopefully not your situation.