I would suggest the 16800 or 168000.
The 168000 were only produced for two years, and so there's a limited production aspect of collectibility right there. Very nice examples with nice patina can fetch around $7-8k for just the watch, again depending on patina. This was also the era when the glossy dials were susceptible to 'spidering' if you are into that sort of look (depends on the collector)
16800 matte dials are another option as it has been mentioned, but the difference between a matte dial and a white gold surround dial are about $3-4k apart.
As for the most affordable, as it has already been mentioned, would be a 14060 from the 90s. In this era, the no-date watches will always be cheaper than ones with date.