Todd,
It might help if you know the pit bosses well and they know that you are avid chip collector. They might even have the boxman count down every stack of $5 chips when no one is playing and put the chips you're looking for aside (at the back of the rack) until you come wandering back thru the pit later. They say "Hey Todd, table 3 has 2 of those chips you were looking for". You stop by and the pit boss might tell the boxman to sell you those chips at the back of rack. You throw in your $10 and get your chips. If you know bosses in every pit and on every shift, this could happen. Just helping out a long time casino customer and not expecting nor recieving anything for the gesture.

It could happen like that and they way George described it, you can see how thorough the search was for the house mold $5 Venetian.