Help with functions

I'm having trouble trying to create a function. I'm new to functions and
I'm trying to figure them out but I can't even get something simple like
this to work. I believe I should be able to do 'SELECT getprice('text1',
'text2', 'text3', 'text4') as price' but all I get in PGAdmin tool is syntax
error near getprice. Is my SELECT statement wrong or my function. I did a
createlang on plpgsql before I started. I'm running 7.2.4.

CREATE FUNCTION getprice(text, text, text, text) RETURNS float8 AS 'DECLARE
v_itemnum ALIAS FOR $1;
v_custnum ALIAS FOR $2;
v_pcid ALIAS FOR $3;
v_branch ALIAS FOR $4;
BEGIN
RETURN 0;
END getprice;

' LANGUAGE 'plpgsql';

Patrick Bye
Programmer / Analyst
Westfair Foods Ltd.
pbye(at)westfair(dot)ca
(403) 291-6538