Can I claim a deduction if I made a charitable gift to a non-profit by purchasing a travel package that the non-profit was auctioning off at a fundraiser event?

I would need to know how much the NP paid for the auctioned item but it seems the difference in that price and the price I paid would then be a deductible contribution.  Certainly the full price I paid would not be deductible as I did receive some value for my "contribution".  But it seems some amount would be.