The Piece of Disney Movie pins were released once a month during 2011 and 2012 and are LE 2000. The cels of the pins from the first year were cut from one continuous section of movie (about 78 seconds worth). Animated moves duplicate each frame to cut down on the number of unique frames that needed to be drawn, so that means that someone may have the exact cel you do, but overall they are pretty unique. Since the first year pins covered a time slice, there are usually quite a few that are less desirable than others. Ie. Dumbo had maybe 1/3 of the pins with Dumbo in them, and the rest were other animals.
The second year, they raised the price $5.00 and used more scenes from throughout the movie, but in general, these they did duplicate exact cels more than the first year, so there are more pins with similar scenes, but overall, there were fewer 'bad' scenes - thus I think the second year pins are more moderately prices as there are more pins that are acceptable to have in a nice collection.
There are other threads and resources on the internet to show the variety of cels that were in each released movie.
They are no longer making these pins, and it is doubtful at this point they will ever resume them. The craziness at the releases was getting out of hand, but I think the biggest issue had to with getting permission from the movie division to use the actual movie cels in pins.
As for traders, unless you have access to Disney events (Florida, D23), the parks, or Disney Studio Store Hollywood, you will likely find it difficult to get access to authentic disney traders that people want at a reasonable price. I'm sorry to say there are not many options for those in other locations to get in on the ground floor of desirable pins at cost.