No idea. If you have access to an Apple Store, the genius bar should be able to confirm the diagnosis of what the problem is at no charge. They could also quote a repair cost, which is likely to be for replacing the display.
You may be able to get a replacement cable from PowerBook Medic or ifixit for and do the repair yourself:
http://www.powerbookmedic.com/
http://www.ifixit.com/
Both these sites might have the cable separately and also have installation instructions. I'm not sure exactly which Mac you have, but I did see some inverter cables for around $30, although they were out of stock at the moment, and I saw that the installation was considered to be very difficult.
If you can get the cable, but don't feel up to tackling the job, you could try an AASP. You could also look at an online repair service like DT&T:
http://www.dttservice.com/macbookpro.html
I have never used DT&T, but they have a good reputation and can probably quote you a price.
Good luck!