Need some suggestions...

I have a huge backlog of knitted goods that i've created…. mostly childrens sweaters and adult sweaters. i have been thinking about having a raffle or contest, held either on my website or blog, wherein the prize is one of the items and a portion of the proceeds goes to a charitable organization. does anyone have any info, suggestions, clues etc. on how i could conduct or set up something like this? I want to be able to show that it is legit and on the up & up... Any/all suggestions would be helpful