Where do you guys look?

[flyguy33]

I'd like to find a GMT Master (16750 or 16700) in good, doesn't have to be great, condition that will be a watch I intend to wear on a semi-regular basis.

I'm reasonably knowledgeable but nowhere close to being an expert, most of my watch buying experience is with more modern watches that have fewer potential pitfalls.

I'm struggling to find places to search to find the right watch to fit my needs and I was curious if some of you could share your process for seeking out watches like this that are findable but take a little effort to make sure you are getting a good/reasonable version.