Nope, not interested at all.
Yeah sure! I'm making/planning one right now.
Yeah sure, I've just never thought about doing it.
I'd make one, but the developer program fee stops me.
I'd make one, but I don't own a Mac.
I'd make one, but I don't know how to do it. It's so complicated!
I'd make one, but I have others reasons why I won't/can't do it.