Still, though, say your player has his character walking through a bazaar on a world and picks up a purple, egg-like thing. The natives love them. They eat them, and they are, indeed, eggs.
How much?
The GM things about a carton of eggs today and says that they cost Cr2 credits.
What the GM should do, to be a little more accurate, is estimate what the eggs cost in 1977.
Say they cost Cr1 for two cartons. Spend Cr2 and get the fifth carton free.
That's a fine analogy, but just how many eggs do you get in the standard Imperial egg carton?