Coloured Stripes

On my computer screen. Five to be exact. You can probably see more (its complicated because I took a picture of the screen????) Anyway they shouldn't be there and apparently it will only get worse as the screen deteriorates. I believe the screen itself can be replaced but its tricky presumably because the screen and computer brain bit are all in the same area - You can tell I am not that technically minded (it's an Imac - quite an old one. They used to throw this problem up occasionally not now though)

Does anyone have any experience of this or have had one of these repaired and if so how much?

I really would love a new one but financially can't justify it. Why do all technical things seem to go at once? We are also experiencing car problems at the moment.