Easiest way to tell is to hook it up to another monitor, if it doesnt do it on that then it's generally the screen, sometimes(rarely) can be a pinched cable but not likelyAnother way I can usually tell is sometimes if you move the screen a bit, gently shake the screen (Very gently!) and it does more lines, then it's easy to tell thats what it is
If it is the screen you can get most screens on
ebay for like 80-90 bux unless it'd an HD screen, then it can be pricey
I would buy if i had $$$ too, but I sink all my money in my car right now lol
If you wanted to fix it though I can replace screens no problem