INT. A SHOP. THE WALLS ARE COVERED WITH THE FLAGS OF THE WORLD. TWO MEN SIT BEHIND THE COUNTER.
MAN 1
I don't understand it. We should be fighting them off.
MAN 2
Fourty years. Fourty years since our last customer. Fourty long years. What we going to do?
MAN 1
Same thing we always do. We go to work.
THEY GATHER SOME FLAGS AND LEAVE THE SHOP.
CUT TO:
EXT. THE MOON. THEY ARE OUTSIDE THE SHOP.
MAN 1
Flags! Get ya flags 'ere!
MAN 2
Only a pound, stick em in the ground!
END.
Not laugh out loud but I liked this. Made me smile. 
They should have moved to Palestine.
I think it works better if just the men are transported to the moon and not their actual shop as that is what I read it as.
Or as an alternative, maybe if it is set entirely on the moon and an astronaut has no flag to put on the surface when out of the blue a flag salesman appears with an array of flags from different nations. (Especially if it was Armstrong and he thought he was the first man on the moon and he gets usurped by the salesman). Just a thought, interesting idea though.
Yeah, not great, it was a case of from head to screen in about 3 mins. I like Nigel's thoughts about Armstrong getting there and finding the shop or just a lone seller there already. Might try a re-write based around that.