DBMM ruleset can be bought by:

UK - Monarch Military Books:  http://monarchmilitarybooks.com/Default.aspx   

UK- Amazon: http://www.amazon.co.uk

Australia - Olympian Games: http://olympiangames.com.au/shop/product_info.php?products_id=130&osCsid=0ef036fb10478a4fca667f4772496126

Italy- Games Academy: http://gamesacademy.mm25.it/

USA - On Military Matters: http://onmilitarymatters.com/pages/

Army list are sold by:

UK - Caliver Books - www.caliverbooks.com