Also, if you want to get into knockoffs, there is a shrunken knockoff of TM2 Megatron which is black and green which I really liked. I have a knockoff of RiD Megatron I like to have stand in for the unproduced Universe Megatron toy.
Additionally, for those who like obscure toys, and they are official, the Happy Meal Beast Machines toys were released in a variety of colors in Australia at Red Roosters. I think there are 5 variants of it out there.
Here are some pictures of some variants, like this green Megatron dragon, Jetstorm and Tankor:
You can get these guys pretty easily on ebay from australia, but shipping costs a lot.