Beemax Beehives are polystyrene, they weigh almost nothing. They winter well, no insulation needed. The temperature is constant throughout the hive in summer, no hot spots. They DO NOT sweat since they are not plastic. They have been used in Northern Europe (very cold) for over 40 years, many with no replacements or repairs since they do not rot. They need only be painted. They are much easier to put together and contrary to what many people will try to tell you, they are not "delicate", they handle very well..
Before I bought my beehives I did some research, and by all counts polystyrene hives consistantly produce more honey, they hold more bees since they have a constant temp.
Of course if you are going to cut and build your own, wood is the way to go. All hives are shipped in parts, polysytrene needs no glue or nails, just a firm hand. As far as cost, very little difference.
Here is where I get mine... http://www.homestead.com/beekeepers/Simpsons.html
You can also e-mail or call Mr. Simpson, an older beekeeper, he has done some research on the subject. He recently told me a medium blue, polystyrene hive will consistantly produce more honey.
I am a new beekeeper, and would never dare to give advice on beekeeping itself, but I am a person who researchs a subject to the point of distraction. So far, I must say, I really love my polystyrene hives.