Goblin Cannon and Ironworks

[Komatteru]

Do you announce an a spell or ability first, and then pay for it, or vice versa?  I mean, it is necessary to pay the cost first before you can announce a spell or ability?

The interaction I'm wondering about is with Goblin Cannon and Krark-Clan Ironworks in play.  Can I announce the activation of the Goblin Cannon, then sacrifice the Goblin Cannon to pay for its cost?  I know I can't announce it twice and then sac both the Ironworks and Cannon.

[DEA]

you announce, then pay for costs, then the ability is put on the stack

[Jebus]

you announce, then pay for costs, then the ability is put on the stack

Actually, you announce, put the ability on the stack, then pay costs.

The first thing that happens when you announe a spell or ability is that it goes on the stack.

Then you make all descisions for it relevant to playing it, then pay the costs.

To answer the original question, yes you can do that.