If you are allowed to serve based upon the facility and school rules but need a license to do so you may try a local Elks lodge or Knights of Columbus group. In our town these organizations will provide the services and license for a split in the profits from the liquor sales at the event.
Our auction is held at a golf club. They give us the space for free because it is early April and just before the "season" starts. Because it's not held at the school we are able to serve alcohol (though it's a cash bar).
I'm sure the laws vary by state. I know in my state for any organization to serve alcohol they have to apply for an ABC license, a certain percentage of the lead volunteers have to have (and pass) ABC training, etc. Basically the same laws as any restaurant serving alcohol apply to us. That doesn't even get us into the where is it held - zero tolerance policy on school property issue, or anything else. Having gone through the training, etc. with another organization I will always vote on paying a vendor to do it!
I would like to hear from other groups if you are able to serve alcohol to parents at the auction? I have heard that we are not able to serve alcohol but we would need to have an outside vendor. I have brought this info to our board and our president still wants to serve alcohol. thanks.