The Society for Human Resource Management once estimated that every time a business replaces a salaried employee, it costs the company, on average, 6 to 9 months' salary. For a manager making $40,000 a year, that's $20,000 to $30,000 in recruiting and training expenses; that is a lot of money.  (READ MORE)  
http://www.robertstevenson.org/robert-stevenson-blog/it-costs-a-lot-to-Lose-an-employee