Re:
Given it's a promotional giveaway, I guess it's entirely possible it was specced with non-catalogue colours to be on-brand for the competition promotor (who I'd guess to be Reebok).
Couldn't say if it had any additional value - bikes of this age and spec can be sadly found in skips. But perhaps to a collector of Reebok memorabilia (especially if came with any competition details) it might bump the price up. Personally, I'd be doubtful - but it's a nice example and those old marins are nice to ride (especially with shorter stems and riser bars for older backs).