Not to threadjack, but I've been kicking around a similar idea, and maybe it will give the OP some ideas.

My idea is to have a tournament at Pacific Pinball Museum with a $30 entry. The entry includes one play on each tourney game, and admission to the museum for two days. If you don't make the finals on day two, you can optionally take home a free pass and come some other day.

After your first entry, you can replay the games for $15.

After your second entry, you can replay the games once more for another $15. Therefore, your total tournament expense will not exceed $60.

The top novice prize would be a pinball machine - a mid-range EM, provided by the museum, sponsored prizes (like translites, t shirts, etc) and small amounts of cash for other novice entrants, maybe down to around 8th place.

The expert prizes would be cash. This way, everyone - novices and experts have a chance to win something.

As Bowen said, the whole thing needs to be fun "for everyone" even those who go in thinking "I don't have a chance."

That's one of the main reasons I run my objective-based Pin Golf for Pin a Go Go. It's a fun, social format. Experts like it because they're forced to play familiar games in new ways. Beginners like it for the chance to meet others and because since the goal isn't score, they have a chance. At every single PAGG I get players telling me they met new people, and that was the highlight of the event for them.

Group play is more social than single player qualifying. Single player qualifying is in some ways, more "pure" and competitive, however. Suit your tournament to your intended audience.

With formats that can take a whole day, a potluck is not a bad idea. Stern sponsored one of my events with a lot of translites so we held a potluck contest and the winner got one. 15 dishes showed up (and a lot more women competitors, btw). This kind of side stuff is not derivative - it gets people who aren't purely players interested, too.