I was having an interesting conversation with someone about recipes yesterday.
Are you able to buy more than one of the same recipe?
For example if I buy a high end recipe from Basil at one of the terminals, sell it, then enter a completely new dungeon. I meet up with Basil again and he happens to sell the same recipe. Can I still purchase it or is it limited to one sale per character?
As far as I know (and someone else should confirm this) you can buy the same recipe as many time as you want I have bought and sold Dusker and Wolver Recipes, which I have also bought and learned myself.
However, I noticed yesterday while I had a Vile Strike recipe, and I was down at the halway point buying recipes again. Vile Striker showed up, but it had a 0 next to it, indicating it was out of stock...I believe this is because I still owned one in my inventory, but not sure though. And I did not have enough money to try and purchase it and find out what it would say about it.