Sorry I read you wrong there, BG. Yes, the 120 is a very good looking knife. It does surprise me that resin casts of the knife sell for that much. That's pretty insane. Personally I'd rather get a Buck 119 and dull the edge for a "prop"...it's shorter in length and thus less "screen accurate", but it's an actual knife with a metal blade and not a resin cast so it's more "authentic"...and it's much cheaper.
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I thought the seller was selling a replica of a model of knife that is used in the movies. "These are (This is) exact replicas of (a replica of) a full size Buck 120 knife (a model of knife) that is used in all of the Scream films (that is used in Scream)" is how I read it.
To me, if he meant he was selling a replica of the actual prop used in the movie, he would have said "These are exact replicas of the full size Buck 120 that was used in all of the Scream films" (ie I have the actual full size Buck 120 prop that was used in all of the Scream films and these are exact replicas of that knife) and if he meant he was selling a replica of the actual knife prop that was used in the movie then he would have said "These are exact replicas of a full size Buck 120 knife that were used in all of the Scream films" (ie Replica props of a Buck 120 knife were made, and these are the actual replica props that were used in all of the Scream films).
Also, he lists a facebook page with the name "spazcustomreplicas"...not sure where people would infer "I sell the real deal actual props used in movies" from "customreplicas". It seems pretty clear to me that he's just selling an unofficial replica (or else he would have used the term "licensed" or "officially licensed") of a prop from a movie.
Edit: Didn't see CK's post before replying. He could be banking on the fact that 120s are no longer manufactured. For instance, Luke Skywalker's lightsaber was actually just a Graflex 3-cell flash handle with rubber grips and a calculator bubble strip. You can buy a replica of the Graflex 3-cell flash that is fully interchangeable with the actual Graflex 3-cell flash (note, I didn't say a replica of the lightsaber, which would include rubber grips and a calculater bubble strip...just the Graflex flash) for more than what you can find an authentic Graflex flash for. And people do buy the replicas. It just saves fans who have money the hassle of trying to find an authentic vintage item to salvage for a prop, with the risk that the vintage item may not be in pristine quality and may be damaged or show signs of wear. Additionally, if you're really passionate about accurate costumes it's a pretty bad idea to just go walking around waving around an unsheathed real Buck 120, which is what you would be doing if you were pretending to be Ghostface from Scream. And most of these types of people go to conventions, where having an actual weapon is banned. He's also advertising towards fan film or stage productions, where you can use the flexible resin prop with much less chance of bodily injury than using a real Buck 120, even if you did dull the edge.
Again, I don't agree with the ridiculously high price he wants for the cast replica. There are other listings for resin replicas costing sixty and eighty dollars, which are more reasonable and comparable in price to auctions for actual Buck 120s that are about to end. I just think there may be reasons someone would be willing to pay for a replica as opposed to the real deal (eg, pristine looking replica you can possess immediately vs an authentic item that you'd have to spend time hunting for and is potentially damaged or worn, and safety for use as a prop)
And besides, the less real knives movie fans buy the more Buck 120s are around for collectors and Buck/knife afficionados.