You will generally find that if you use a mailboxes ect or something like that to ship, you will pay more than double for shipping. Thats how they make their money.

Here is my suggestion for that plane. Have the seller get a letter size file cabinet box from an office supply store. He will also need a bunch of the foam popcorn. Put the plane and popcorn in the box and fill it all the way with the foam popcorn. No air voids. Lots of places keep that stuff, it is expensive to buy also. A lot of places throw it away.

Box the rest in a seperate box.

Take it to grey hound and put it on the bus. It will cost between $30 and $40 to ship the plane probably. UPS won't take one that big, and fedex will be about double. If the box is smaller, it will be cheaper.

Don't get too small of a box. You want it packed well. I had one where the guy left the horizontal stabs out both sides of the box. I can not believe the freight company took it that way. More surprized that it got there in one piece. Good luck.