In order to insert the Euro symbol (€) in emacs, you can use the Unicode character U+20AC by typing
C-x 8 RET #x20AC RET
You can put this in the macro “euro” by adding the following lines to your .emacs file:
(fset 'euro (lambda (&optional arg) "Keyboard macro." (interactive "p") (kmacro-exec-ring-item (quote ([24 56 return 35 120 50 48 65 67 return] 0 "%d")) arg)))
and restarting your emacs (server). The euro sign can then be inserted by calling the macro:
M-x euro
If you have any other symbol you know the Unicode value of, you can probably do something similar.
AstroFloyd's blog 
Good man thanks
C-x 8 RET euro RET
will enter the euro symbol
I get:
C-x 8 RET
Insert character (Unicode name or hex): euro RET
Invalid character
Do I need to install a package first?
nope, just enter either the unicode name or code – either of these:
euro sign
20ac
Yes, `C-x 8 RET euro sign RET` works.