This is a retired set, hard-to-find (an ebay search only turned up some in the UK, starting at over $200 without shipping). It is unused, though the box has been opened to look at it (and it's dusty from storage). All pieces and manuals are in the box.

http://mindstorms.lego.com/eng/products/dsdk/index.asp
From the packaging:

SET:#9754

PIECES: 578

AGES: 9

Lego Mindstorms has created a kit that includes everything you need to make your own moving,bleeping,thinking,interacting Star Wars AT-AT and other DARK SIDE robots/droids.

From the packaging:

THE MICRO SCOUT-The Micro Scout is a Lego microcomputer that acts as the brain of your robot.

Use the built-in light sensor,motor and sound to bring you robots to life.

Create familiar Star Wars Imperial Vehicles like AT-AT or create your own menacing robots.

The Micro Scout has a built in light sensor and motor.

The Micro Scout has also 7 built in programs none of the programs can be over written or erased.

NO PC REQUIRED

SITH APPRENTICE:

Encounter the dark side of the Force through guided training missions.

Follow step-by-step building instructions and guided help from Constructopedia.

Activate your robots with the special powers of the Micro Scout.

SITH LORD:

Test your skills by building even more advanced robots that walk.

Follow full building instructions to create the Destroyer Droid.

Than take on the challenge of creating the Stepper and X-Walker.

SITH MASTER:

Fulfill your destiny by creating the most challenging robots of the dark side.

Follow full building instructions to created a fully operational Imperial Walker.

Take the ultimate challenge to create your own Sith Master vehicle like the Trade Federation AAT.

WITH THIS KIT YOU CAN ALSO BUILD:

1.AT-AT

2.DESTROYER DROID

3.STOMPER

4.L-8GO NAVIGATOR

5.DROID STARFIGHTER

6.STEPPER

7.X-WALKER

8.SWAMP CREATURE

9.AAT TANK

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