My vote is for a new battery. I just replaced mine...it was the original Motorcraft with 8 years and 98,000 miles on it...but they can go any time. My son's '98 Dakota pick-up (37,000 miles) had problems starting, just clicking, but holding the key would eventually cause the starter to turn the engine over. He would also lose his radio settings when this happened. Still, the dealership replaced his starter under the 30 day/1000 mile used car warranty...they felt the starter windings may have been bad.
When he went to pick up the truck the same problem existed. So the tech ran a test on the battery and found it had a weak cell. So now he has a new battery AND a new starter.

Makes me wonder about the dealership's diagnostic capabilities, though.

- Jim Our yardbirds: Belvedere, our '96 Jeep Cherokee, 4.0L ATX, 85,000 and going strong Spencer, our '03 Chrysler PT Crusier, 2.4L ATX, 28,000 and just getting started