You can replace them cheap enough and ask those that fix them for details.
If the laptop switches on but the screen remains dark. In some cases a faint image is visible on the screen. This problem can be caused by a faulty fluorescent light, inverter, video cable or a problem on the motherboard.
http://www.laptoprepair101.com/laptop/2007/01/31/replace-screen-inverter-fix-backlight/comment-page-16/ is pretty good as the replies show where people find the 20 buck part.
I have Dell Inspiron 630M and after investigating it seems that
there is no power o/p on backlight display card. Do anyone know the technical specification like power i/p and o/p with Pin no's on this small board ?
The helpful information will be appreciated !