The first question is whether the nonprofit may sell the wine at all.  This is a question of state law and many states have severe limitations on who can sell alcoholic beverages, with or without a license.  Certain nonprofits may be able to get a special permit, but you should check your state law to see if you can get into trouble if you just sell it at your event without getting the permit.  A lot of these limitations are not regularly enforced, but there isn’t much defense if you get caught selling what you shouldn’t be selling.  There may be people who don’t like your organization who would be happy to report your violation to even a reluctant law enforcement officer.

Assuming that your nonprofit is a 501(c)(3) charity and you got the wine or some other property that you can sell without a problem, you should account for the value of that gift as a donation on your financials, normally at fair market value.  If it is worth more than $500, your donor will want you to sign a Form 8283 confirming receipt of the gift, though not the value.  If you are lucky enough that the gift is worth more than $5000, the donor will need an appraisal report to accompany the tax return on which the donation is claimed and the 8283 is filed.  (See Ready Reference Page: “IRS Requires Substantiation of Contributions”)

As for unrelated business income tax (“UBIT”), you are not likely to be subject to such tax, even though the sale of the items is unrelated to the business for which you are exempt, if you sell it only at your event.  To be subject to UBIT, the unrelated business income must come from an activity that is “regularly carried on.”  Income from an annual fundraising event, even though unrelated to the mission of the charitable of the organization other than providing funds for its operations, is not considered regularly carried on.  (See Ready Reference Page: “Nonprofits Often Worry About UBIT”)

If the gift is wine that you can’t sell, you should still account for it as a contribution.  You may be able to use it as part of the menu at your fundraiser, a staff holiday party, or a donor recognition event.  With a gift of wine, it is unlikely that it won’t be useful in some way.