1.Parisara Ganapthi or Eco Friendly Ganapathi
This webpage is interesting. They have detailed instruction and a video for making Ganesha idol, check them out!
2. Hindu Blog
This blog has a you tube video for making Ganesha. Take a look and probably you will make your own Ganesha!
Buy Eco Friendly Ganesha and save Mother Earth :)
Here is our 'practise ganesha' that I made from clay that we had at home. Results were good and it has encouraged me to make a nice one for the festival :)