Amazon.com has an error

My wife showed me an error at Amazon.com the other day.  A book listed for sale that should be listed for about $10 is listed for $100!  You can buy that book brand spanking new on other websites for under $10.  We tried to find some way to contact Amazon.com to tell them that they should fix that error – no one is going to buy that book at $90 more than it is worth!  But we could not find any way at all to contact them to notify them of their error!  If you know of a way to contact them, let me know!