How can I create a Goatperson?

I've got the special edition of Desktop Dungeons, which includes the Goatperson DLC. As I understand it, among other things this includes a new playable Goatperson class.

I've been playing Desktop Dungeons for a while now and still haven't seen a way to create a Goatperson. Do I have to progress to a certain point before I can unlock it?

In order to unlock the Goatperson, you need to purchase his building at a relatively steep price of 3000 kingdom gold. The building seems to first appear when you beat the Frozen Tundra quest. But you'll likely need to keep questing for a while before you can actually purchase it, since your kingdom bank needs to be upgraded to be able to hold that much gold.