Backing is expensive stuff actually, but I use a 30 pound braided dacron. That way, I don't have to put so many yards onto a reel as the 20# that everyone "suggests".
As for lines, reserve $45 - $55 for one! Although I'm still partial to the good ole Cortland 444 lines, I have an Airflo Sixth Sense on my regular rod. I've been very pleased with the way it handles, the stiffness and it's durability have been above satisfactory!
SA Ultra lines were also nice and in the mid-range, price-wise. But now that I think of it I think SA has stopped marketing them with the Ultra name. I may have to look into that.
The RIO lines are also quite nice and not too outrageous. I've had a couple of those on "client" rods and they've been holding up nicely.
The Sixth Sense line that I've had for probably five seasons now
(and that's my use) is still in great shape. And I don't clean them or treat them at all! I'm brutal on lines, but then they only get thrown on the Little Missouri too. Relatively clean...
At any rate, I brought it back up because it is a "delta" taper, very similar to the Wulff Triangle Taper lines - as opposed to standard weight forward lines. I've always liked the way these throw, particularly on roll casts and for line manipulation on the water! It's like throwing a giant tapered leader!
Lines are pretty critical, like I said, plan on spending that price range on one. If you get any less than that you're going to have a line that isn't as stiff, won't last as long and doesn't float as nicely!
Any
more than that is just silly!

Sorry, all you Sharkskin guys!