you can say that again

come again

A polite formula used when one has not heard or understood what has been said, or to indicate surprise.

final say

The right to make a final decision.

have a say

To (receive the opportunity to) voice one's opinion.

here we go again

An expression of frustration upon seeing or hearing something bad repeated.

I'd say

It is my estimate or opinion.

I'll say

Used to indicate emphatic agreement

let's not and say we did

Indicates that the speaker does not agree with a proposed action, and does not wish to participate.

needless to say

Clearly, obviously.