$3.00
The smallest is the Lego Duplo Vet. It contains only 4 pieces.
When Star Wars Episode 2 was originally released Lego did make a geonosis set that came with 2 geonosian minifigures, 2 droid minifigures, a cannon and a geonosian fighter. The set was called "Geonosian Fighter", it was released 2003, and its set number is "4478".
Yes, many Lego minifigures and pieces only are produced in one set, sometimes discontinued, making them very rare.
Lego Star Wars started in 1999 and their first set was released, Lego X Wing. This set is basically a star fighter which came with a few minifigures and a cockpit for them to sit in.
It depends on how much you build
The most expensive Lego set ever was the Lego set number 10179 ultimate collectors Millennium Falcon which originally sold for $500 on Lego.com.
2000000$
Lego Indiana Jones sets typically cost ~5-30 U.S. dollars.
LEGO doesn't sell military set . If you are ok with much lower quality of parts check out best-lock toys. There are companies that specialize purely in creating custom Military / Army Minifigures or Model kits out standard LEGO parts and some custom elements.
It is most likey to be $12.99
Anywhere between 138.49 to 399.99 (400)
The LEGO Death Star set has over 4,000 pieces. It is one of the largest and most complex LEGO sets available, featuring intricate details and multiple minifigures from the Star Wars franchise.