Bottling Plagues and Such

[LichPlease]

Are there any rules (official, 3rd party or homebrew) that explain a way of crafting/buying vials containing diseases, similar to crafting/buying poisons?

[Mr.Spastic]

Not that I know of. It would mostly lie with your DM on how you would due those kinds of things. The big thing is that in the standard DND setting people wouldn't know about microorganisms.