Non-Profit wants my house. Need Tax advise?

I have a non-profit that wants to by my house at a discount from the market value. In turn I'll be able to make a donation for the differance between the discount and market value to that non-profit group to save on my taxes. Does any one know what kind of discount to give. The market value is $160,000. Tax bracket is on the low end. Any help would greatly be appreciated.