Does the wick look something like this?
That's just a centrifugal humidifier wick. Nothing special about it. They come in probably a few hundred different diameter & height combinations. It's just frickin' paper, it can't cost much in bulk from the manufacturer/distro end.
Try online for bulk or wal-mart in the pharmacy section for singles to three packs. Find the area where they have humidifiers, I noticed some replacement wicks there the other day. If the design of the water tank & fans in your humidification system is similar to the Habitat Monitor HMII that I have, the diameter of the wick isn't critical, just as long as it's within a half-inch to inch or so, it should be fine. They also had some rather tall ones that could easily be cut down into two wicks.