How much is an 1904 20 st gaudens worth?

The first St. Gaudens double eagles were released in 1907, so a 1904 St. Gaudens coin is not possible.

Please check your coin again. If you have a 1904 double eagle with a Liberty head design, it's worth between $1000 and $1100 depending on how worn it is.

If you have a different date with the St. Gaudens Standing Liberty design, please post a new question with that information.

Copy each of these links into your browser to see images of each design:

http://coinfacts.com/double_eagles/liberty_with_motto_double_eagles/1904_liberty_head_double_eagle.htm

http://coinfacts.com/double_eagles/saint_gaudens_double_eagles/1910_saint_gaudens_double_eagle.htm