Mike,
Not all were purchased at the cages. Some came from main coin redemption booths. As they are not legally supposed to sell strikes while live machines are still in the casino, I feel it best not to name the casinos to protect those who were kind enough to sell them to me. All the casinos were on the strip and I hit Harrahs, Treasure Island, Venetian, Paris, Monte Carlo, Imperial Palace, Caesars, Flamingo, Bellagio, Mirage, Excalibur, Tropicana, MGM. Let's just say, ask and you will be pleased at the response you get from many of the friendly staff at most casinos. In many casinos, even though they were not supposed to sell strikes, cage employees told me to go ask at the change booths. This proved to be successful in a few instances.