I'm a huge fan of the film and might be tempted to buy it again. I'm sure there are collectors out there who buy every re-release or re-package of their favorite movies, Harry Potter or Star Wars fans for instance. It's not a huge amount of money to sacrifice.
Meanwhile we're still waiting for The Abyss and True Lies to make their Blu-ray debuts.
According to this article over at HitFix, Cameron will be doing a new interview for the anniversary Blu-Ray. Also, there will be another reunion at SDCC, this time including Cameron. Since Fox is going to have a presence there, I wouldn't be surprised to see that panel also show up on the BD.
I've seen the big box (which may be the best blu-ray ever released) go for less than what they are asking for this edition. A new interview with Cameron and reunion panel doesn't do it for me. Perhaps when it goes for $10-15 (and it will) I might get it.