An LT-40 is a high wing trainer made by Sig. I looked to see what a wing would cost and it would be 70 dollars. A Tower Trainer ARF is that much.

Yes the wing will be built with 2 pieces of folded coroplast, but with a full length spar so it will be a one piece wing once you are done. You will put a small wrap of coro in the center to help join the 2 pieces together. Read over the plans carefully and study the pictures on how they are put together. I've given you an avenue to travel that may help you, but the best thing you can do is spend a bit reading on how to do it. I studied all the plans on STTB and read lots of threads before I gave it a shot. Don't be afraid to look at other options. You could scratch build a wing from Balsa. You might find a used wing at a hobby shop that could work. If you have a club near by, lots of fliers have pieces of planes lying around that they will part with to help someone out. Finding a club would be a good idea anyways so you have someone to help you learn to fly. It's a lot more expensive and time consuming trying it on your own.

Good Luck,