There might be an exception if you owned the items for more than one year before you donated them, but then you would definitely need a written appraisal by a qualified appraiser. You would also have to fill out Form 8283 and have it signed by both the qualified appraiser and an appropriate official of each organization that you donated to. For the details see the following IRS references. Since it's an unusual situation, and the amount you are talking about is quite large, you might want to consult a local tax professional.
Publication 526, Charitable Contributions
Publication 561, Determining the Value of Donated Property
Form 8283
Instructions for Form 8283
