So the [photo]play ski porn and  show and prove premiere in my area last year was held in a local freeride shop. so if your shops have a semi large building you might be able to do it there and bam you have the presenting sponsor. Then just move all of the store's product out of the way (you can move those things that it is displayed on. and you have a large open area. then your sponsors don't just have to be local. If you attract enough people to this you can go bigger. I think the one I went to last year had around 300 people, and some of the sponsors were: K2 skis, Salomon, Smith Optics, Oakley, Dakine, POW Gloves, Sublux, Freeskier, Whistler Blackcomb (and this is in WA) and the Summit at Snowqualmie. then you could get some of the companies to have give aways (rafels for charties are always good) Now you have more ways of attracting people. a key thing to do would be to advertise, a few weeks ahead of the show, tell your friends about it, have them tell their friends, put up posters at your school if you are still in school. Tell people on NS about it. Do the same a week before the event. and then heavily premote it the few days before it.
Another great way to attract people is to have a local brewery have free or cheep beer avalible for people in attendence.
One thing that you should realize is that you should not be doing this to make money. make it  so that all procieds will go to some local charty, people love that shit. And if you have it look like you are trying to make money for yourself, you will find it harder to get sponsors. this event should not benefit you at all other then that it will be a good thing to put on a resume.