Clip a Photo out in Photoshop

We have a super high res stock photo of some balloons that we need to have carefully clipped out (including the strings). This will be going on a dark background. We would like the clipping applied on a layer mask or with paths and saved as part of the file so we can edit later if necessary. Essentially, we want to clip the balloons and strings away from the light grey background. We have a tight turnaround on this. I'm including a lower res version of the file here so you can review, before quoting.