5DII without grip: $140
http://reallyrightstuff.com/ProductDesc.aspx?code=B5D2-L&type=0&eq=&desc=B5D2-L%3a-L-plate-for-Canon-5D-Mark-II&key=it
http://www.kirkphoto.com/L-bracket_f...5D_MarkII.html
MKIV: $180 I have this RRS one! The Kirk L-plates are great too, though!
http://reallyrightstuff.com/ProductDesc.aspx?code=B1DMkIII-L&type=0&eq=&desc=B1DMkIII-L%3a-L-plate-for-Mk-III-%26-Mk-IV
http://www.kirkphoto.com/L-bracket_f...D_Mark_IV.html