Why are boxes so expensive? Aren't they just cardboard?

I am heading to the post office today to mail a gift for my new nephew and my college laptop to my college brother. You'd think the computer would cost more to package up, being that it is an expensive piece of equipment. But wouldn't you know that I can pack it up with a bunch of bubble wrap and slip it in a regular box for minimal costs... while the cloth covered cork message board for my sis- the new mom- doesn't fit in ANY normal boxes. Well see, I could put it in a huge one, but it is relatively flat and I'd hate to spend the money for all the extra weight and size and all that plus how silly it would be to have a huge box filled with popcorn to mail a lil cork board.

I checked out FedEx to see if they might have a nice "flat"-style box. And sure enough they do. I was thrilled. Til they rang it up. 13 dollars for a box. yeah right.

My verbal response: "Um, I need to think about it."
My thoughts/translation: "Are you crazy?!?! It's cardboard! And we're in a recession, donchaknow?"

The entire project only cost me the price of ribbon and pushpins (don't tell Amber. I don't want her to think I am too cheap to spend money on my gift!). Why would I spend 13 dollars for the cardboard that goes around it and will just get shoved into a pile of boxes below the stairs when it arrives? So, I did what any frugal gal does when she needs something but can't afford the outrageous price. I improvised. Do you like it? Cut apart the box that a photo frame from Kohl's was in as well as the packaging for the baby gate. All the rest of our packing tape and duct tape later, you have a box ready to mail. I even matched the colors up so nicely, from a distance it looks like it came that way... sort of... til you notice the yards and yards of tape. Now I just need to wrap it in brown paper so they will accept it.

13 dollar box, FORGET YOU!!! (oh, and good luck opening this box upon arrival!)