Art show for charity?

So I am part of a school club that focuses on a charity called Invisible Children, which is an organization that donates money to help the relief effort in Africa. We want to put on an art show to raise money, but my mom who used to be an art gallery director told me that artists get hit up all the time for charity shows and it would be breach of contract with their galleries to sell their work anywhere else but the gallery. I guess that means that we would have to find undiscovered artists? Is there any other way to hold an art show and still raise money without crossing any legal or social boundaries?

Also, are there any undiscovered artists out there in the southwestern USA region who would like to help us out? ;)

Check into the Cradle Project-it benefits Aids Orphans in Africa and is quite neat. I am making a cradle to donate myself-but the ideas and info might help you too. Check with your local art groups-many artists are self representing-like I am and are not affiliated with a gallery. The local art society-museums etc should have listings and give you ideas. You could post on their sites or call to make an inquiry. Also the artist/students from the local college. Call their art dept.
As a working artist- I do get "hit up", people expect you do dso things for free just because you have a talent. I myself work with lower income neighboring schools to do murals and teach classes. I am paid, but minimally and donate way more-its a pay it back situation for me though and my return is high in my opinion. Don't be afraid to ask the groups-all they can say is no-right?

Put ads in the local Arts newspapers, flyers at art schools

make the art yourself. then put ads around town. not in newspaper tho, cuz that costs money which u could be using to donate.