If you don't mind a Disney Cruise Line one you could try the cruise board. There might be a Castaway member that would give you thier old lanyard (you get the same lanyard the first 4 times you cruise). I'd give you one of ours, but I don't know what I did with them.
If you are looking for trader pins Mouse pins online is GREAT. I have used them several times. You can buy a grab bag of 25 pins for $37.50. They guarntee that the pins are good pins and tradeable at all Disney parks. Right now you get a free lanyard with each 25 count grab bag. So you can get the pins and a free lanyard at the same time. Good luck.
Party City has CUTE lanyards! also, for buying pins on eBay please feel free to follow the link in my signature. It can be very helpful. It is quite big so I suggest reading the first few pages and the last few. Enjoy!