The antique watch business is a multi-billion dollar business. However there are a lot of fakes out there so buying an antique watch requires careful research.

A Brief History of Time
Some knowledge of mechanical watches will help a lot in judging the approximate date of manufacture of the antique watch:

1500s Peter Henlein of Germany created the first pocket watch
1660s Christian Huygens invented the remontoire
1680s Repeating mechanism for bells and sounds patented
1700s Rubies used in watch movements
1750s Enamel used on watch dials
1760s Lever escapement invented
1800s First self winding watch invented
1840s First watch to have winding and setting through crown
1914 World War I popularizes the wrist watch
1914 First wrist watch with alarm
1926 First water proof wrist watch
1956 First watch to display day and date
1960 First watch to have scratch-proof dial

Sources of Antique Watch
Antique watches of many established companies are available such as Rolex, Omega, Universal Geneve, Angelus, Vacheron & Constantin, Seiko, Benrus, Breitling, Gruen, Zodiac, IWC, Movado, TAG Heuer, Hamilton, Ingersoll, Shakosha (Citizen watch company of Japan) Gallet, Wittnauer, Bulova etc. There are a lot of sources on the internet selling watches online. Good buys can be found at auctions and second hand markets but the authenticity of these antique watches are doubtful.

Maintenance of Antique Watch
Maintenance of the watch is very difficult. The parts are not easily available and antique watches cannot be repaired at all watch shops. So do make sure that the seller also guarantees their repair if the need arises. Most antique watch sellers also provide maintenance and care manuals for the antique watch. Be sure to follow the instructions.

Cost of Antique Watch
These watches are available anywhere between $300 to millions of dollars depending upon the make, the date of manufacture, the history of the watch and the jewels in the watch. The market price of the antique watch is determined by its snob appeal and social acceptance.

Antique watches make wonderful gifts and give the wearer a distinct and artistic look. Owning one allows the owner to combine artistic appeal and nostalgic charm. However, they are rather costly in general and need a lot of maintenance and care.