Arguably the most frequently asked question I receive is "what's my watch worth?". The easiest answer is, "It depends".
Some watches are surprisingly common... like the 1941 Martin so they don't really command a premium unless they are exceptional examples. Other watches are less common, and you're lucky to find them in any condition, like a 1936 Randolph. It wasn't even shown in catalogs. Then you have the class of watches that are popular designs but plentiful... like an Electric Pacer. Lastly, you have popular designs that also less common, like a Pacermatic.
Determining what something is worth is a factor of how common it is, how popular it is, and, of course, what condition it is in.
One thing is for sure, if the case is solid gold it's worth more than the melt value of the case (unless the case is totally trashed).
My project watch is an interesting example to try to value. It's a 1954 Clifford. It was only made for two years and came in a fairly large (for the time) solid 14K gold case. It retailed for $135 in 1954... that's about $1,300 in todays currency.