Hi Rachel,
You're obviously aware of my not-so-secret obsession with all things
Vinylmation. I am a HUGE Disney vinyl collector and am proud to count many
Park Starz in my collection.
While there is regular Vinylmation trading, both open and mystery box, available in many of the larger resort and theme park gift shops, Park Starz trading is much less common.
The only place I've heard offering Park Starz trading has been the D-Street store at Downtown Disney. They have experimented from time to time with open box Starz trading. If this is available at the time of your visit, you'll see a plexiglass box on the counter by the register. If there's a vinyl displayed that you'd rather have than your duplicate squid, simply ask the counter clerk if you can trade. As a word of warning, you should know that you can only trade Starz for other Starz, not Starz for Mickey (or Duffy) shaped Vinylmations.
There are also occasional vinyl trading nights that take place at the Contemporary resort. Collectors gather here to trade duplicate collectibles and swap information about upcoming vinyl releases. These can be great fun and there is often no admission fee. Check the first link above for details.
Happy trading!