Need Advice On Buying Motorbike

I want to buy a small Honda Cub and have the option of buying and registering it in either Thailand or Cambodia. I travel between the two countries several times a year, and wonder what would be the best approach. Is it easier and cheaper to cross the border into Thailand on a bike that is registered is Cambodia as compared to crossing into Cambodia on a bike that is registered in Thailand? Or doesn't it make much difference one way or another? I also wonder about the costs and hassles behind the registration process in both countries. In which country would it easier and cheaper to register and buy a small bike? If anyone has any experience with this subject I would be very happy to hear from you.