Sometimes, the question is accompanied by almost no information. For example, "it looks like the one you have here," followed by a URL to a photo of a general pocketwatch on my website.
Sometimes it will include an Elgin serial number and nothing else.
Either way, it should be clear that the question can not be answered from such vague information. It's like saying "I have a Ford made in the '50s, how much is it worth?" The answer would be a range from $50 to tens of thousands of dollars. Sometimes I am tempted to answer the question that way.
But I don't. I am not an appraiser. Although there is no licencing requirements in the US, appraisers are credentialed by professional appraisal associations. There are also IRS rules regarding income for appraisals.
Also importantly, in many states appraisals are considered domain expert opinions, and may be subject to litigation similar to malpractice. If a perceived, or self-represented, expert gives an opinion, and turns out to be wrong, they may be subject to a lawsuit to recover loses. A professional appraiser can get insurance for that.
If you want to know the value of an antique, contact a professional appraiser. They will probably need to see it, so try to find someone local. For those collecting or working on vintage watches, either as a hobby or as a profession, be careful about statements regarding the value of watches.