its plain and simple, as nice as sponsors will be, you might not get them, seeing as its a small hill, and no one really wants to sponsor a slopestyle event from ontario. local shops will be willing (im guessing), try smaller bike names, they might, or contact say norco, cause they're always up to promote events.
try local bike shops in and around Milton and Oakville theres some that might be willing to sponsor it like maybe gearhead , oakville cycle , spokes and slopes , cyclepath ???? just something to consider
Then why wouldn't the actual mountain produce the marketing, as they are the ones who will be making the profit. As much as it needs rider help, I think a better response would come from a mountain saying "We're going to put on a comp, want to sponser?", instead of the riders themselves.