Thank you for the reply, mighty Leviathan
I'll polemize a little bit.
What if the key cost was only about 1k for a good route? There would be more freighters on that route and the profit would be only a couple of wings per ton. It's how economy works. And players had to work hard to get the money. Even with profit of 3fb/ton, PCs with a small freighter with 40t of cargo space could get only 120fb per jump. Let's say one route takes them two weeks. 240fb/month, investment in ship (let's say 40k) will pay off in ... 14 years (20 years if profit was only 2fb/ton)! It may sound great for a business-oriented noble who thinks in long term, but not for PCs, who don't want to wait. Although, for PCs It might be nice source of extra income that helps them cover costs of fuel and repairs (PCs like trouble).
Also, in the past there was plenty of starships and plenty of jump keys, so even if most of them (keys) is lost, many should survive and can be used again (maybe after realignment). Because the number of ships is also greatly reduced, old keys could satisfice significant percentage of need (Scravers wouldn't resign from such occasion).
Moreover, I think that even without total control over keys Charioteers could be filthy rich (like it's with computer piracy in our world - over 40% of software worldwide is pirated, but Microsoft, Apple, Oracle and others are still biggest companies in the world). Also, as practice shows - the more expensive good, more likely it's gonna be forged/copied/pirated. So, the higher price would cause black market to grow (it's inevitable, we can see it clear observing our "war on drugs").
But anyways - with your assumptions (that are probably much more canonical than mine), is it possible to play a group of (relatively) free space vagabonds with a starship and no home? From Alustro's Journals it looks it's possible, but how? Hire Charioteers regularly (which may be problematic if you are a outlaw or want to keep low profile)? Make a quest for each jumpkey (because they are so precious)?
Maybe my thinking is wrong - too Star Wars-ish? In FS space travel seems to be a really big deal (compared to Star Wars), but even FSR Player's Guide says: "It is not recommended that players begin gameplay with spacecraft - they should earn a ship through roleplaying", so players should (be able to) earn the ship, eventually.