I know with METRO you can chill in the "lobby" of the Convention Center without a badge. The TCC is a public facility, so we can't charge you to just sit and relax!
Sure, you can't see the shows that make METROCON what it is, but at least the guests tend to just chill around, anyway! Artist Alley is also in a public space, so that's SOMETHING. Panels are also usually open to anyone (unless it's a VIP Only panel). And you actually can buy a pass to the Fantasy Masquerade without having a con badge since it is a separate ticketed event, and that's just $10.
We can't force you to buy a ticket, but I hope you decide to, though. That way you can catch the shows!