[david in germany]

Originally Posted by porshah

Buying pre-owned is a great idea. Just remember to buy the seller before buying the watch. As mentioned by Irishsig, buy from reputable sellers. Forums are a great start. If possible try to do a local deal where you can meet at a reputable watch dealer who maybe able to inspect the watch for you. As tempting as it may be to save a few bucks by buying just the watch, try to buy a watch that is complete with box and papers. Ideally the watch is still under manufacturer's warranty. Just like buying a BMW, do your homework.

I have picked up two Tag Heuer from eBay. Both were from shops. One I picked up and paid in person and one the seller was very thorough with the photos. Both are in amazing condition and function.
Check seller history and do plenty of research before buying. Search for as many confirmed fakes and counterfeits as you can to find online and see the flaws so that you can determine what the real one looks like when the time comes. From my research I can normally catch a fake Tag at first glance now and even have contacted eBay because of some I identified (to protect others).
Best of luck!