I don't think it's a good idea to try and fit in 'X credits equals X money' right alongside with 'items on later planets are more expensive because game'. That leads to people like MerchantMan twisting their brains into pretzels in order to figure out how the fictional economy of a scifi porn game works (it doesn't).
Either credits have a value or they don't. Right now they do, except when they don't.
I fully agree, but hey Word of Fen is Word of Fen. It's my choice to take that and pretzel my brain around into sensible numbers. Good thing I love pretzels right?