Here is the defintion of Quid Pro Quo Contribution:
Quid pro quo—A quid pro quo contribution is a payment made to a charity by a donor partly as a contribution and partly for goods or services provided to the donor by the charity. For example, if a donor gives a charity $100 and receives a concert ticket valued at $40, the donor has made a quid pro quo contribution. In this example, the charitable contribution portion of the payment is $60.
My question is: It we have a silent auction and a person purchases a basket for $100, they technically are not "donating", are they? But because they are writing a check to the PTO, they could call it a donation, so we should issue these receipts disclosing that they did not pay more than the value and thus it is not tax deductible? But really it isn't partly a donation and partly for the basket. It is all for the basket.