In fact, during last year's roadtrip I carefully checked the level each time I refilled gas, but I think the higher heat of highway driving seemed to minimize the leaking during that trip.
My OEM radiator was a plastic-aluminum composite, and appeared to be leaking at the junction between those two materials. According to other people, this is apparently a common source for leaks and generally is easier to replace than repair.
I got an estimate for a new radiator, installation labor, and coolant flush and Lamb's quoted me a total of $629 (parts $424, labor $169, tax $35). Furthermore that was just for another of those "composite" plastic radiators ($292 just for the radiator)--if I wanted a premium all-aluminum radiator it would be $80 more.
I had done some searching the previous night and knew that I could get an all-aluminum Jeep radiator online for about $130 plus shipping, so I knew Lamb's prices seemed a bit excessive. When I mentioned the price that I could get the radiator for, the guy at Lamb's recommended I buy a few of those radiators and sell them on eBay (which ironically was where I found those prices).
I decided to just buy the new radiator off eBay and install it myself. The instructions from other people on the net seemed to indicate it was relatively easy and could be done in about 2 hours, which is pretty close to how long it took me. I ended up saving and re-using the same coolant since mine still seemed pretty clean.
During the installation I puzzled over the presence of extra connections on the new radiator but not on my old one, which are apparently for an automatic transmission--I just left them disconnected on my manual Jeep. Another complication was caused by the bolt holes used for the fan shroud being just barely a different size--I ended up shearing off the head of one of the four bolts, but I figure 3 bolts should be enough.
Click to embiggen