About the prices calculations - we can use that guy's table, but the new forum screwed up the formatting. It might be tough to decipher it.
edit: managed to get part of the costs. It seems balanced for small ships. A 1000 ton freighter (optimized for J6), seems to generate ~8 Mil/run with a monthly cost of ~1 Mil.
edit2: I have no idea how the current prices are set on the table in the core book, especially the J4-J5 shift. And also why the heck LOW passage is more expensive than a basic passage in the J5 and J6.