If you have a bar at your premises then keep the ticket prices down to between $10 and $15. If you dont have a bar at the venue or you arent making anything from it, then you can afford to make the prices a little higher. Get someone in to do the catering unless you BBQ more than once a year, then it may be worth getting your own equipment. Make provisions for poor weather.
Again, do as much of the work with volunteers as you can. Ask local businesses to sponsor you by providing resources or lending you equipment. BBQs are a great social occasion and it helps if you can make it on the same date every year so that people look forward to it. Truly one of the great fundraising events for your community organization.