You can buy just the clay bar. Some AutoZone's sell the Clay Magic 200gm size bar. Sherwin Williams carries the 3M 200gm bars. Below are a few places that sell large or multiple clay bars:
Mother's Clay Bar (three 80gm bars):
http://www.waxstation.com/cgi-bin/st...d=&mfg=mothers
3M Clay Bar (200gm bar direct from 3M):
http://www21.3m.com/dr/v2/ec_MAIN.Master
Pinnacle PolyClay:
http://autogeek.net/pinpolclayba.html
etc etc
Just to note: many, including myself, cut the claybar into thin slices and after claying a section, throw the slice away. There is always a fear that after you fold and stretch the clay to expose a fresh surface, some contaminents may resurface and possibly scratch your paint.
Below is a video made by "The Veed" for those that want to see how claying is done. Just right click and save:
hi-resolution:
http://www.tslugmo.com/car/clayhi.wmv
low-resolution:
http://www.tslugmo.com/car/claylow.wmv
Also Detailing Dude did some ratings on claybars he has used, but remember these are his opinions and the ratings for some bars, IMHO, are rated a bit too high (no avg or poor ratings):
The Blue Clay Bar:
I recently tested 3M's and ClayMagic's clay bar and have the same one that is imported from Japan (even has the same exact patent numbers on them, LOL). However, there is a tremdous price variation between the two with 3M's being around $5.00 less. I have found the 3M one for around $18. My Rating: Very Good.
The Yellow Clay Bar:
I recently tested Mother's, Zaino's and Zymol's clay bar and they appear to have the same exact one (although there is no patent number, LOL). Mother's clay bar is available for is available for around $18 as well but I was given my Zaino clay bar so I am not sure of the price. Zymol's clay bar is $80.80!! My Rating: Very Good
The White Clay Bar:
I tested Meguiar's clay bar a years ago and was not at all impressed. Meguiar's clay bar retails for $10. My Rating: Good
The Grey Clay Bar:
I recently tested Lusso's clay bar and the quality appears to be right in line with the 3M, ClayMagic, Mother's and Zaino. Lusso's clay bar retails for $14. My Rating: Very Good
The Red Clay Bar:
I have not recently tested AutoMagic's red clay bar. It contains a mild abrasive. I would recommend that this bar only be used in a professional bodyshop atmosphere. I will not give this product a rating.