We own a condo that is professionally managed and rented all year. We donated a week use of the condo to a registered charity. There are 3 different values: the cost that the occupant pays to the management company ($3,000), the owner (our) proceeds from a rental ($1,500) and our finally out actual out-of-pocket cost for the wee ($35) - not counting the lost potential revenue. What amount may be deducted as a charitable contribution, if any?