Go to eBay and purchase sealed booster set pins that cost around $2/pin. That way you know they are authentic Disney pins. There are cheaper pins ($0.50/PC) sold in bulk on eBay but I can guarantee you that they are what's called scrapper or counterfeit pins. Now, the CMs at WDW or DL will trade with both pins because they're not allowed to reject a trade request as long as it meets the trading requirement. That's why most of the pins on CM lanyards now see scrappers

But now that you know that I hope you would consider using only booster sets to trade so there will be less scrappers in the park instead of more. Have fun!