A good COMEX you will have to build or have built. Like much in life, it depends on your budget, how OCD you are about small details and how far down the rabbit hole you want to go. Some of our guys have franken builds that are pushing ten grand, some have reps that cost less than a hundred quid, sometimes one guy has both.
http://www.pf-818.com/catalogsearch/result/?q=Comex
If you can live with any of these, go for it. They are cheap enough and can be greatly improved if you are inclined. A genuine COMEX has a very distinctive square Centre to the O in COMEX. The dial can be exchanged for a better one from Vietnam at a cost of about $150-200, the case can be shaped and improved on, the crystal can be swapped out for something more convincing. All this can be done stage by stage or you can just accept it as it is, because who is going to believe any COMEX not in a safe is genuine anyway.
If you want to check out the other end of the spectrum
http://jewelryandwatch.com/
Even these can be improved, but you are talking $1200-1400 just for a case