As for the estimated cost of Starship, a cost inferior to $300/kg(, sometimes below $100/kg) seems confirmed all over the internet after a quick research, although the prices are varying, with many articles(, e.g.,) speaking about an aim below 10$/kg.
However, interestingly enough, the only contradiction i found came from wikipedia, since a capacity of 100.000-150.000kg for a current launch cost of $100.000.000 would imply a cost of 666-1000$ per kg.
I've probably made mistakes while checking all of this, so feel free to dive deeper in order to explain the differences between SpaceX's estimates and the wikipedia page.
It's also absurd that the fit line dives down to be cheaper and earlier than an optimistic projection that will likely move further to the top right as time progresses. That's a chart with an agenda, not an analytical regression.