The Micronauts weren't released all at once, rather they were introduced as part of a series, as shown below.

    SERIES 1  (1976)

 ___   Time Traveller                ___   Hydra
 ___   Galactic Warrior              ___   Galactic Cruiser
 ___   Space Glider                  ___   Hydro Copter
 ___   Acroyear                      ___   Mobile Exploration Lab
 ___   Photon Sled w/fig             ___   Astro Station
 ___   Warp Racer w/fig              ___   Biotron
 ___   Ultronic Scooter w/fig        ___   Microtron
 ___   Crater Cruncher w/fig         ___   Stratastation




    SERIES 2  (1977)

 ___   Pharoid w/Time Chamber        ___   Neon Orbiter
*___   Pharoid (Type 2)              ___   Rhodium Orbiter
 ___   Acroyear II                   ___   Thorium Orbiter
 ___   Baron Karza                   ___   Aquatron
 ___   Andromeda                     ___   Battle Cruiser
 ___   Force Commander               ___   Giant Acroyear
 ___   Oberon




   SERIES 3  (1978)

 ___   Galactic Defender            *___   Phobos
*___   Star Searcher                 ___   Nemesis
 ___   Taurion                      *___   Cosmic Control Base
 ___   Solarion                     *___   Satellite Survey Station
 ___   Microrail City               *___   Micropolis Monorail Set
 ___   Interplanetary Headquarters  *___   Interplanetary HQ (Type 2)
 ___   Galactic Command Center      *___   Galactic Command Ctr (Type 2)
*___   Micropolis Megacity




   SERIES 4  (1979)

 ___   Antron                       *___   Alphatron
 ___   Membros                      *___   Betatron
 ___   Repto                        *___   Gammatron
 ___   Terraphant                   *___   Carrio (carrying case)
 ___   Hornetroid                    ___   Rocket Tubes



   SERIES 5  (1980)

*___   Kronos                       *___   Emperor
*___   Centaurus                    *___   Megas
*___   Lobros

A "*" denotes an item which is rare. Good luck finding these!