how to format money in an sql statement

 

Hello All,
I am trying to format money to be inserted  to an sql statement.  I currently have this
str = str + "'" + a.Trim + "', '" + b.Trim + "', '" + System.DateTime.Now + "', money, "

when i hard code money as 2.00, for example:
str = str + "'" + a.Trim + "', '" + b.Trim + "', '" + System.DateTime.Now + "', 2.00, "
it works fine, but when i am using a variable like
 dim money as double

money = dr("amount").ToString()
 
 as with the 1st example i get the error message:

Input string was not in a correct format. please help me.
 
-Kagome