Replace LCD or just inverter on iMac 20"?

My iMac 20" (Core 2 duo A1207, 2.16 GHz) LCD screen suddenly became grey developed vertical and horizontal lines (see image). There is also what looks like a crack on the top left corner where there is a white patch.

The computer works fine otherwise on a secondary monitor (I am actually using it now)

The question is whether I need to replace the entire LCD or just the inverter?

How long do these screen last? I have had the computer for 6+ years.

Does nt look like it will be worth replacing it with a new one considering how much they cost. any ideas on where I can get a used replacement (I live in Sweden)

Thanks. The screen is not dim a such, most of it is actually white with horizontal grey bands and the vertical green/red/black lines on the left that start from what looks like a crack mark on the top left as you can see on the attached image.