I have done it both ways. A Big Bar Mitzvah the first time that cost a bunch. The 2nd child we had family only and the party for the kids was at laser tag. Family had a big dinner at Maggiano. Both ways were wonderful in different ways. So I would say do not give in to peer pressure or the fear of disappointing your child. That said, if you are having a big party........
You have probably already talked to Bill Cody. He is worth it. I'd advise you to skip the extras on everything else! No video montage, no napkins with your childs name, etc... Make your own easy decorations. Even homemade food is okay. Choose the Temple or a rec center for the event. Maybe a button person if not too expensive, but Bill Cody can provide all the entertainment you will really need. I'd say skimp on everything but him!
But, you can also look for a teenage DJ to save $$.