ball-park figure informal
ball-park estimate informal
ball-park amount informal

American said it is not sure yet what the final rental price will be, but $10 to $12 is considered the ballpark figure.

Coming up with a ballpark figure is not that hard to do.

I shot him a ballpark figure, and he's been calling ever since.

That brings us to a ballpark figure of 500K.

We talked about a ballpark figure of a hundred million.

That will give you a ballpark figure, but even those underestimate how much it actually costs.

Maybe you should get some kind of ballpark figure before we go any further.

I asked him if he had any kind of ballpark figure in mind.

I have long had a sort of ballpark figure in my head.

A woman is never supposed to betray her age, but a ballpark figure isn't too bad.