The best way to ship wheels and tires, assuming the tires are mounted is to pair them up into two packages. Get some large cardboard boxes and cut three cardboard disks the diameter of the tire for each pair. Place one disk between the two wheels (wheel faces in), and one on each of the outer sides. You then need to wrap the assembled pairs with good packaging tape (2"). Wrap the tape around the package several layers thick in at least 4 places making sure the assembly is tight.
As far as shipping costs, weigh an assembled pair on a bathroom scale then go to
http://www.ups.com/ and plug in the "to" and "from" zip codes, the weight and how you want to ship - double the price and there you have it. Hope this helps.