I'm an RPF regular since 1999. Long time prop collector and builder. I've done a lot of research on this prop. I used to own an Illusive Concepts HiC. I ended up selling it to Adam Savage of the Mythbusters (he's local to me). I'm 100% certain this is an Illusive Concepts product. The backside with slathered on fiberglass resin wrapping around from the sides, the way it's put together with wood screws. The side panels are the same poorly made solid one piece castings also attached with wood screws. The sides are warped, commonly seen in this product. All done exactly the same way the IC product was put together. As far as value? In it's current state with all the damage, I would say under $1000. Also, keep in mind that Sideshow Collectibles has come out with their own version of the HiC 1:1 that is way better quality for $7000. Sorry, but in my extensive, first hand knowledge of the original and in my opinion, this is NOT an original LucasFilm prop.
Sorry to be the barer of bad news. But the good news is, you can fix it up and it will still be a good prop piece to keep in your house. Let me know if you have any more questions.