That’s almost correct. The microtransaction is not a ferrystone (the fast-travel consumable). It is a portcrystal (a one-time additional fast travel location). You cannot buy ferrystones with real money.
Ferrystones are found or purchased rarely. It’s a clearly intentional decision to force you to explore the world on foot and weigh whether the current danger is bad enough to use a precious ferrystone to get home or if you should try and push through.