I'm guessing 2 Billion because any more would be out of the reach of the average player.
Said the same thing elsewhere but it probably
does depend on how many credits the "average player" has.
FDev will probably look at the stat's and then decide if Carriers should be within the budget of the top 10% of players, the top 5%, 1% or whatever.
Thing is, to use CGs as a comparison, it's usually
really easy to get into the top 50% of a CG, a bit harder to get into the top 25%, considerably harder to get into the top 10% and insanely difficult to get into the top 1%.
The people at the top end put in a
lot of effort and, as a result, there's huge gulf between the top 10% and the top 1%.
Same thing applies to Credits.
50% of players might have, for example, less than Cr1bn, 25% might have 1-5bn, 15% might have 5-10bn, 9% might have 10-25bn and 1% might have more than Cr25bn.
If FDev decide that Carriers should be within the reach of the top 25% of players, they'll be priced at between Cr5bn and Cr10bn.
If they decide Carriers should be for the top 5% then they might be anything up to Cr25bn and if they decide they're for the top 1% then they might cost more than Cr25bn.
Ask yourself, honestly, how common you think FDev might want Carriers to be.
Do you think they're going to want Carriers to be a common sight, in every system where players can be found?
Check out any thread on Credits and you'll find there are plenty of people who seem to get their jollies from making number go up.
It might be VOs, massacre missions, skimmer missions or passenger missions but there are plenty of people who just relentlessly farm these things to gain massive amounts of Credits.
There are players out there who, like those who put a
lot of effort into CGs, put a
lot of effort into gaining credits.
Don't be surprised if it turns out Carriers cost more than you think they will.