Just to clarify, the the 'holders' are the plastic things that actually hold the badge. How they affix to your persons really isn't that big of a deal you can use pretty much whatever you want as long as it's affixed above the waist where we can prominently see it.
This year we DID have both Lanyards, and the clips, (because we had a backlog of past years lanyards) but we blew through the lanyards rather quickly on day 0. So I believe we are down to just the clips.
However, if you have your own lanyard, it works fine. They also sell the really spiffy looking kumo lanyards in the dealers hall. And from a quick glance while helping people setup a few other vendors have some cool looking ones.
So, to sum up, it's the Plastic part that matters, it'll have 'Kumoricon 2010' printed on it so that we know you have checked in and gone through the registration line.