You say you're still covered under Apple Case? Call Apple. Numerous individuals have had Apple replace their screen. If your display has started to go pink, due to the dying backlight, Apple will replace it.
If not, then you can replace *just the backlight* yourself. Though it is tricky. The backlight can be purchased from
http://www.jkllamps.com/laptop.html
The size of the CCFC tube in the Pismo's display is 292mm x 2mm, so BF20292 is the model number you want. the cost is about $15.00.
Truth be told, it is difficult to accomplish, but hardly impossible. You can follow my guide to replacing the LCD display at my webpage, at
http://homepage.mac.com/scadboy/lcd/
Once you get the panel out, it's a simple matter of dissasembling it and popping in the new CCFC tube, and stitching everything back together.
But, call apple first.
hope this helps