2022-12-08 : You can sacrifice any Goblin you control to activate Skirk Prospector’s activated ability, including Skirk Prospector itself. Note that once you sacrifice Skirk Prospector, you won’t be able to activate its ability again, so if you’d like to sacrifice multiple Goblins including Skirk Prospector for mana, be sure to sacrifice Skirk Prospector last.