Space helmets with visor. I have 4 still bagged, 3 new but unwrapped. $15 / ea.
Inflatable set of planets: Mercury, Venus, Earth, Moon, (extra moon?) Mars, Jupiter, Uranus, Neptune and Sun. Saturn as a ring attachment, which is the point of failure and has ripped. Could probably be fixed by slitting, inserting old soccer ball, etc. $20/set
I have an air pump I can sell for inflating: $10 Sun is large (18" diameter: thankfully , not to scale) so plan your inflating accordingly.
Legends of Space rocket models $20. 2 Revell Snaptite Space Shuttle kits $10/ea.
Plastic jello mold with astronaut and star shapes $8
Plastic astronaut figures (more than 20), lunar rover, flags. Suitable for cake decoration. $20
Two inflatable astronauts $15/ea
xtronaut 2.0 board game. I bought this new recently, and opened it up to examine it, but it has not been played with. 2-6 players, ages 8+ ,60 min play time. It does not look hard to learn; Players build a rocket mission, and play bad events on opponents. $25