It depends.
*If you're trading with a CM off of a CM lanyard (while they're on-stage), then they and you *have* to trade one for one.
*If you're trading with another guest or a fellow collector/trader at a Meet or at one of the known WDW pin-trading locations, then whatever makes everyone happy. Maybe your jumbo pin is rare or an LE & the other trader really needs/wants it, so they'll offer multiples for your Jumbo single. The reverse can also be true - maybe the smaller pins are Limited Editions(LE) and the Jumbo is just a big rack pin, so a one for one works out for the two traders.
Be careful about trading at DTD at the tables near the Pin Store. I've run into what I would call a lot of pin sharks there, my last trip was quite disheartening. Many (not all, but many or most) of the folks who have books at the tables there can be somewhat unscrupulous and are referred to as 'pin-sharks' or 'sharks'.
One practice that I've run into is that they will somehow have tons and tons of hard-to-get cast lanyard (or Hidden Mickey) pins in their books. They seem to trade with cast members & get desirable cast lanyards with their own cheap traders (maybe even the infamous 'scrappers'). Then when folks want the sharks' lanyards, the sharks ask the Guests to buy some particular LE pin/s. This way they can get around Disney's rules about Guests selling pins while on Disney property. The shark gets some LE pin, the unsuspecting Guest gets a 'Cast Lanyard'/'Hidden Mickey' pin and the shark can then turn around and sell that LE pin on EBay - it's a great deal for the shark, since the LE pins the Guest bought for them have cost the shark virtually *nothing*. There's not
always something "hinky" about this practice, sometimes the Guest just really wants a pin from a trader/Guest and they have nothing the other person really wants, so they freely buy something....
but especially at DTD? - forewarned is forearmed.
We were just at WDW earlier this month. With the exception of our one visit to DTD, I enjoyed almost all of our trading experiences, especially when I was able to just give pins away. I had received a couple of the Tink/2-pin Dreams sets this trip and I gave each set away. One at my resort to a fellow Guest who had just started pintrading (and she had almost *no* pins), and one to a CM when they needed some pixie dust for another Guest. I overheard a CM in AK ask a Dream Team member there if they had any of the Tink sets, so I pulled my set out, gave it to the CM and the Dream'er gave me 2 random pins off of her lanyard. I didn't asl for the pins, but the Dream'er asked what she could do (hmmmm...I wonder if that Cinderella Suite stay had already been given away haha). I was happy to help a CM out, the CM was happy to be able to give a set to the other Guest and the Guest who ultimately received the two-pin set was thrilled. I also had a CM give me one of those Daisy "Good Girl" pins and I looked for someone to give it to. There was a little girl who had just bought a Figment lanyard and a few pins in the shop at the end of that ride. I gave her the pin because she was just first starting out. I told her she could keep it or trade it, but that I though she deserved a 'Good Girl' pin.
Here are some of the areas for trading I've found recently...
*Not sure if you're aware of them, but WDW now holds once-monthly Pin Meets in a room at the Contemporary's Convention Center. We've had great experiences there.
*Some WDW resorts have different pin-trading situations beyond trading off of CM-lanyards, say out of CM-books(like at the Wilderness Lodge Pin Cart) or off of a corkboard in the resort gift shop.
*I was surprised that The Studios had the most CMs with lanyards on our recent trip. They had more lanyards than any other park we visited *and* the CMs there were enthusiastic about pin-trading with Guests. Practically every single CM I saw had a lanyard on - this is not always the case in the other parks.
Welcome to the Dark Side...we have pins 
!
agnes!
