Actually for something that equals the iMac display it is not at all cheap. Anything that's affordable is merely decent, and does not come near this old iMac's display.Personally, I wouldn't bother even if you could as that monitor is old and tired and considering it's what you look at while you use the computer you could get something a hell of a lot better without spending an awful lot of money, and there has been a lot of advances and improvements in modern monitor design and manufacture.
Don't put unnecessary strain on your poor old eyeballs!!!
I am talking about prices in India and not in North America