2004 S (no warranty) 55.6k miles

Got back from a run this weekend to find my car leaking a good deal of coolant on to the garage floor. Upon inspection, it looks like it squirted everywhere at some point since dried coolant is on the underside of the bonnet, all over the upper radiator hose, etc, but it hasn't leaked much since (coolant level probably down below the leak(?)). I added coolant and took it in for a pressure test.

It's losing pressure, but only very slowly. Mechanic thinks there may be a small leak in the radiator, and says they won't know if it's fixable or needs to be replaced until they can get in there and take a closer look.

Worst case scenario quote of needing a whole new radiator is about $500 ($190 labor, $310 for the radiator). Here are my questions: are radiator leaks often fixable, or is it very likely I'll be replacing it soon? Does this sound like a reasonable deal on the parts/labor? I'd consider doing it with the help of some friends, but from a few searches of the forums, it didn't terribly simple, and I wouldn't want to put my friends through anything too painstaking. Any experiences or advice?