An organization which is recognized by the IRS as one that can receive charitable contributions can raise funds by many means which include selling merchandise or tickets for an event. The deductible amount for the contribution made is equal to the difference between the fair market value of what is received and the amount that is actually paid for it.
Here the ticket for the concert normally costs $100; this makes its fair market value as $100. Marlene pays $350 for the same ticket. The difference between the two is $250 which is the excess amount paid by Marlene.
The amount that is deductible as a charitable contribution is $250.