Bloodline bidding does not let you convoke and sacrifice goblins to skirk prospector to pay the cost. If you try to tap goins to pay the convoke first, prospector will only see the untapped goblins. If you try to autotap you will get a note saying it it unable to pay costs to cast the spell. It should let you if I am not mistaken since convoke is being used to pay mana and prospector is a mana ability. It lights the card up like i can cast it in my hand, but when I try it doesn't let me.