Not sure what you mean by "quantity" or "all its forms". It establishes the fair market value of the goods or services provided. As discussed earlier in this thread, if the FMV is $12,000 and you purchase it for $14,000, you have made a charitable contribution of $2,000. If you purchase it for $12,000, you do not have a deduction.
You may challenge the FMV, but will need to document the discrepancy.