Cost for repairing the display backlight?

Well, this is a user support forum so none of us are going to be able to give you a cost of what it is going to be. Someone MIGHT be able to tell you what they paid if they had something similar done, but I don't usually see that done on here. However, if you really want to know what it is going to cost, then you can check to see if there is any place around you by doing a Google search and see if there is a place around you that does this type of repair and they could give you a price on what it will cost. You are going to want to be careful though because if you go to a place that doesn't do a very good job, then they could damage other things in the process and then you are going to have to pay for replacement of that as well. I personally would make the drive and go to the Apple store and have them look at it as they could then tell you what it is going to cost to get it repaird. You can have that done at the Genius Bar and they don't charge to take a look at it for you. You can set up an appointment online and they will be ready for you when you get there. This is going to be your best bet, but you can do a search as there are a lot of places out there that do work on Mac products, I have one right over by me that is an awesome place to go that sells used Mac's as well as does all work on them. They do great work and prices are great as well. So if you search I'm sure you can find something that you're looking for, but I haven't had that done to any of my computers so I can't tell you an estimate of what it would cost.