Tax advice: Are purchases from NPOs tax deductible

you want to deduct the cost of the shirt you bought at Goodwill, don't you?

I'm pretty sure you can deduct ad purchses regardless of whether you purchased it from an NPO or not.

I dont know about caps or minimums though

An expense is deductible if it is ordinary and necessary for a business. So deductibility is determined by what you purchased and for what purpose, not whom you purchased from. You purchased advertising space in a publication. Advertising is generally an ordinary and necessary business expense. So as long as the expense was not excessively large relative to the circulation of the publication, it should be deductible.