If this was your candidate, I too liked how it looked and the story, long ownership. If the service history is as advertised, could be a good truck. Seems the owner knows what he has, that is not a bad thing. Many times we try to save $ 500-$ 1,500 or so on the purchase only to spend it soon after, making necessary repairs. Paying a premium up front for the well-maintained truck can yield benefits that last.
https://seattle.craigslist.org/skc/cto/5851033568.html
With the driver's seat wear, I would guess maybe more local miles, frequent stops/in and out of vehicle, as opposed to high highway miles? Of course it is the best color Sudan beige metallic?
Has the factory lighted step running boards, premium package includes rear heat/air, auto climate control, and I think power passenger seat? Note you also have a tow hitch, and the weather tech rear compartment mat.
Maybe a good local interior shop could make a repair to the seat, as the rest of the truck looks pretty good. A real detail job on the inside would make night and day difference. Enjoy the heated seats and that awesome electronic traction control. About the only thing you could add would be the factory DVD player from a junkyard.
Here's a good review of the '03 although Canadian:
http://www.autos.ca/car-test-drives/test-drive-2003-mitsubishi-montero-limited/
Good Luck!