I purchased the blueprint for the personal chest from the man in the market. However, thinking I could just buy another blueprint later, I used the blueprint as part of an offering to unlock fast travel at a whisper. But he no longer has it available to purchase again. Am I doomed?
If you’re talking about Grinnich Don’t worry every 24h he changes articles randomly.
If you’re talking about Whittacker Like all other merchants, he should restore all the items every (real life) 24h. If this doesn’t happen, it’s a bug.
But even if that is the case don’t’ worry because when you upgrade the shop he should have everything again.
If somehow this doesn’t work either don’t worry anyway, because you can still find the item randomly around as a drop or in Grinnich’s shop.
If you’re unlucky and all the things I’ve told you don’t work, you can create another realm just to buy the blue print, since the characters and realms are independent from each other.
If even that way even when it doesn’t work (practically impossible, unless you tried modifying the game files) maybe you removed the object file from the game try uninstalling and uninstalling the game.