There are many ways of buying a chainsaw. You can go to a shop that sells farm tools and buy a tree saw from that shop. The shop owner would help you find the best device for your needs.
For more information visit here-
http://megamachinewarehouse.jigsy.com/entries/general/precautions-to-be-taken-when-shopping-for-garden-tools
For more information visit here-
http://megamachinewarehouse.jigsy.com/entries/general/precautions-to-be-taken-when-shopping-for-garden-tools