If you are seeking these because your windows are hard to roll up there are a couple of temporary solutions.
First and best is to re-adjust the alignment of your window regulator. However, if your window channels are as worn out as mine were, this will help but your deteriorated channels may still bunch up and cause the windows to be hard to roll up, just not as bad.
Secondly, and I did this until I could find replacements: Is to lubricate the channels. Use a Silicone Spray Lubricant and squirt it down the channel. I found this really helped but its only temporary. I had to respray about every month. But it helps until you get replacements.
Dont use a petroleum based lubricant like WD-40 as that will eat at the rubber making things worse.