An authorized apple repairing center told me that the backlight lamps of my mid 2009 macbook's lcd was broken and with 410 $ they could fix them (assembling a new lcd).
So i decided to replace the inverter cable, inverter and lcd panel on my own saving 235 $.
I've never replaced anything of electronic parts, laptop parts and i'm not an expert of computers (hardware and software).
ifixit's guide helped me a lot!
be careful when reassembling all the parts! it is easy to broke tiny cables or similar pieces like wifi, isight cables and the display data.