Thats not exactly correct. You may rightfully claim the "fair market value (FMV)" ie the willing seller and willing buyer senario. For example you my deduct the FMV for items given to you as a gift, from an inherentence etc.
As for multi teeny bars of soap, shampoo etc I assume this would not be an easy task especially when you consider your "ultimate user" and what amount they would willingly or realistically pay.
MisterNice