Appropriate donation amount?

Note: This calendar image is just a ROUGH mockup...the actual calendar will be very different!

calendar2.jpg

Pawsitivity Service Dogs wants to give you a gift when you donate to rescue a dog (we give the dog 900 hours of training so they can live a fulfilling life as a service dog). What donation amount would YOU be willing to give, to receive a calendar of paintings of rescue dogs? :-)

Appropriate donation amount?