The store employees in the airport didn't even know what a lanyard exclusive pin was when we checked out their lanyards on 4/19!!
We had great luck at all four parks. By the end of our vacation the girls (ages 9 and 12) were hunting CMs like Elmer Fudd hunted rabbits!! It was a riot.
Best bet is to check out as many CMs as quickly as possible as early as possible in the day. They literally keep these pins in safes, and the pins usually go quickly. We got THREE within 5 minutes of a CM going on duty!!
Also look for CMs that have a "mystery pin" -- it is on the lanyard backwards (with the rubber or metal pin back on the front of the lanyard). If you want it, you have to trade sight unseen. My 12 year old didn't have the guts, she wanted to know what she was getting first. Since I had some $6.50 pins for the sole purpose of trading, I was willing to give up one of them just to see what they mystery pin was ... it was the tweedle de-tweedle dum lanyard only pin. When my DD saw that I got a "good trade" she grabbed the next CM (about 12 feet away) that had a mystery pin and traded ... she ended up with Minnie Topiary. Note: mystery pins are not guaranteed to be lanyard only pins. I noticed that the pins we traded became mystery pins in place of the ones we'd gotten. So the next guest would've gotten decent pins, but nothing to jump up & down about.
Besides the obvious CMs at pin kiosks, look for lanyard-wearing CMs (and don't forget the suit & tie managers wearing lanyards!!) in stores, bathrooms (janitorial CM had a lanyard), restaurants (over 1/2 of the CMs at 50's Primetime Cafe in MGM had them), and GUEST RELATIONS (we started going into GR just to scope out the CMs behind the counter, if they had anything worthwhile then we'd get in line). Ride attraction CMs do NOT have lanyards.