There are roughly a dozen postings. The majority are written in common, though some are in dwarven or halfling.
Each posting contains, amidst the various claims of being the best and fastest ship to be found anywhere, a flat rate for each mile traveled: there are signs of this not having always been the case, but apparently the pilots have begun to conform to this system of payment.
The lowest rate is 12 gp/mile, by a pair called Thranos and Grakyl and their ship Rabbit's Foot, which is detailed as a "small, swift vessel, but still capable of carrying large cargo or many passengers", while the highest rate is 100 gp/mile, by a group known as the Rolben Trio and their airship Rolben's Hope, described as "One of the largest ships this side of the world, with a carrying capacity of thousands of pounds or hundreds of passengers; but even with this great size, it is still one of the fastest ships in use".
As you read the postings, you also note that some ships have added flat fees for heading to destinations that lack an airdock; both the pair and Rolben's Trio have added such a fee, which is 500 gp for the pair and 1200 gp for Rolben's Trio. The next cheapest rate is 24 gp/mile, but that posting - that of Valshar, a solo pilot who operates a small craft called the Coldlands Hawk - does not have a fee added for a destination with no airdock.