I'm currently in the process of making a one-shot and the BBEG is a Dwarf artificer, but I can't seem to find the class. I know you buy it from the Eberron sourcebook but whenever I pull it up it doesn't show the class as an option to buy, I even looked through other sourcebooks to see if it was moved or a glitch on my end but it doesn't seem to exist. Is it something I'm doing wrong?

They moved it to Tasha’s Cauldron because of the updates to the class. Purchase any of the four subclasses to unlock the base class.