It would be quite embarrassing to spy what color they're using that day from a distance, slap the correct color wristband on, walk up and try to breeze through only to realize yours doesn't have host's printing on it. Or is a different pattern. Or have the same fastener. Or is a different width.
Even if you do get through, lots of people will spot you as a cheapskate.
Even if you do get through, lots of people will spot you as a cheapskate.