If it weren’t for a man named Kent Warner digging through MGM’s trash, there may never have been much of a movie memorabilia market. Warner, a costumer by trade and collector by night, managed to salvage a number of classic film props from several studios, fetching discarded ruby slippers from The Wizard of Oz, the trench coat from Casablanca, and hundreds of costumes that he funneled into private hands.

That was back in 1970. Today, movie memorabilia is a multimillion dollar business, with auctions offering fans a chance to own screen-used or screen-worn apparel and props. One of the largest of the year is set for September 26, when London’s Prop Store will be auctioning off high-profile lots featuring items from Aliens, Star Wars, and other classic sci-fi and fantasy films. Here’s a glimpse of what’s in store, along with the estimated final sale prices once the gavel comes down. (Film history doesn’t come cheap.)

1. C-3PO’S HEAD // THE EMPIRE STRIKES BACK (1980)

The suffocating mask sported by actor Anthony Daniels through months of filming 1977’s Star Wars—in excruciating desert heat, no less—led Daniels to beg the special effects staff to make a more comfortable costume for the sequel. Instead of fiberglass, propmakers used injection-molded plastic. The problem? The plastic quickly shrunk, making the heads unusable. The prop department kept them around as extras in case they needed spare parts. Effects masks from the trilogy are highly sought-after, with Chewbacca's fetching $172,000 back in 2008.

Estimated: $77,000-$103,000

2. THE JOKER’S SUIT // BATMAN (1989)

Now you can dance with the devil in the pale moonlight—whatever that was supposed to mean—in style. This vivid purple suit worn by Jack Nicholson in director Tim Burton’s gothic take on the Dark Knight comes complete with shirt, tie, gloves, and purple leather Oxford shoes. (Jack wore a 10.5, in case you were wondering.)

Estimated: $26,000-$38,000

3. STAR LORD’S HELMET // GUARDIANS OF THE GALAXY (2014)

Peter Quill (Chris Pratt) sported this space helmet for galactic combat in only the second movie to co-star a taking raccoon. (Doctor Dolittle did it first.) Pratt’s movie star head was kept comfortable with interior foam and leather; LED lighting allows the eye sockets to glow red.

Estimated: $38,000-$64,000

4. INDIANA JONES’S WHIP // INDIANA JONES AND THE LAST CRUSADE (1989)

Harrison Ford’s third excursion as the superhero archaeologist demanded a deep reservoir of bullwhips. This one was used for scenes where Indiana Jones attempts a rescue of his father Henry (Sean Connery), among others. It’s made of kangaroo hide and measures 10 feet long. Presumably, the auction house is not responsible for whatever injury you may inflict upon yourself trying to use it.

Estimated: $64,000-$90,000

5. ALIEN CREATURE COSTUME // ALIENS (1986)

It’s game over for anyone trying to top your Halloween set-up if you can get your hands on this “alien warrior” costume worn by stunt workers for James Cameron’s Aliens. The complete polyfoam suit was designed by Stan Winston and based on H.G. Giger’s original concept.

Estimated: $26,000-$38,000

6. MARTY MCFLY’S SNEAKERS // BACK TO THE FUTURE II (1989)

It took Nike decades to engineer a mass-produced pair of the sneakers worn by Michael J. Fox in the 2015 sequences of Back to the Future II. These screen-worn shoes were for shots of Fox walking around and feature a light-up Nike logo on the front.

Estimated: $32,000-$45,000

7. PETER VENKMAN’S SUIT // GHOSTBUSTERS (1984)

Be assured Bill Murray busted ghosts in supreme comfort during filming of the 1984 comedy classic. The zippered one-piece jumpsuit is made of cotton and features the iconic Ghostbusters logo on the right arm.

Estimated: $7700-$10,000

8. GRAYS SPORTS ALMANAC // BACK TO THE FUTURE II (1989)

The perfect guide for the betting time-traveler, this Grays sports records paperback popped up frequently onscreen as Marty McFly tried to wrest it from the grip of adversary Biff Tannen. This is just the cover, though: no actual win/loss records are inside.

Estimated: $1300-$1900

9. SPIDER GREMLIN // GREMLINS 2: THE NEW BATCH (1990)

A true work of macabre art, effects legend Rick Baker designed this spider Gremlin as part of the mutated creature troop for director Joe Dante’s 1990 sequel. It’s undergone some slight restoration work.

Estimated: $13,000-$19,000

10. DOCTOR DOOM’S ARMOR // THE FANTASTIC FOUR (1994)

“Iconic” might be too strong a label for producer Roger Corman’s low-budget Fantastic Four film, which was reputedly made quickly so Corman could retain the film rights to the comic. This impressively-designed plastic suit of armor is probably the best thing to come out of it.

Estimated: $3900-$6400

All images courtesy of Prop Store.