Hi Vin,
This is indeed a reference that many watch fans appreciate a lot. As usual with vintage pieces, especially when very old like the 96 usually are, it is a good thing to remain cautious and meticulous in your research.
Most of the sellers are on Chrono24 from my small experience with 2nd hand watches. This is also where I would start from.
Then you'll have to be very careful, for instance when it is too good to be true (very low prices etc...), you'll have to ask for pictures, especially with the serial numbers (with a magazine showing the date?) in order you can check them maybe with a Patek authorized dealer or a Salon etc...
In the end, it has a lot to do with the confidence you'll have in the seller. That's not an impossible task but there is a little work to do.
About price now. We usually don't talk about watches valuations as it is a very tricky subject. If someone has a wide range to mention he can say it but we prefer that more indepth prices discussions remain private, thus via our Private Message feature. i hope you can have some info this way and good contacts with purists.
About dealers, it is very hard to say as well, some people may have 1 or 2 names to tell but the risk is to rise shilling or biased issues and so on. Thus we prefer that people share them via PM too.
You'll have in the end to make your own opinion about the prices and who you can trust as a seller.
However, we would be delighted to discover how things work for you about this project and especially if you find your watch! That's a great reference to consider for sure and it will be something you'll wear with great pride.
Now, what layout is another story
Best, Mark
PS: don't forget we have a Search function on the forum that you can use to read about the 96