Constellation Gold 1970s thoughts..

@Zaccardelli1994 -
As you say, a later C case in 18k and in pretty good condition but less desirable than its earlier siblings.

it’s a much easier conversation to have if you tell us what the asking price is.

Unfortunately, the easy answer is that the true value is what someone will pay for it.

You’re pushing the upper limits of ‘vintage’ watches as followed on these forums.

These watches are only just coming out of the woodwork so don't really have comparable watches to judge against.
( I’ve not seen one on OF or in my auction alerts)

It’s 18k so has an intrinsic value but the market for C cases has softened in recent months.

If you like the day date (and don’t mind the later dial configuration and 1021 movement) then if it doesn’t go above your upper limit I think you’d be doing ok.

However, there is a small (but dedicated) group of C case collectors on the forum who may offer an alternative opinion.