I see regular posts like this here. There isn't really any contact, but I think Apple targets large organizations rather than smaller groups. There's frequent posts here from parents of autistic children and it is usually recommended they contact a national organization since Apple is more likely to work with them rather than give an iPad to an individual. I'm not sure where you fall on this scale. Try http://www.apple.com/contact/ I note the specific omission of any sponsorship link on the N. American site though there is one for Apple Australia.
As Limnos said, Apple really doesn't have a donation or grant program. Your most likely avenue would be to approach an Apple Dealer, of which there are a few in Sitka, or other local businesses and ask for donations of goods or funds with which to buy such prizes. Local businesses are much more likely to be responsive than would any multinational corporation who, as I'm sure you can envision, gets probably thousands of such requests every year.