Wheh...... this is probably no help, and I wouldn't even begin to give you a ballpark. But.....

When you say "unfinished" do you mean it was never completed and the construction was stopped at some point? Because how would they know the pump and filter work if it was never "finished".

I think what your trying to say is it's not "open" or functional right now?

I only worked on pools in the North East, so some of these construction techniques from warmer weather climates I've never seen (this being one of them).

But just to impart a few things when I look at the pictures.

Its been empty for a while, possibly more then 2 seasons. A good sign the "fix" wasn't inexpensive.

If the "concrete", tile, and what appears to be masonry block, are the actual water proof shell, then the large cracks seen in the second picture would worry me as a contractor bidding on it. While most of the other things in the picture appear to be cosmetic, those cracks are definitely wide enough and big enough to cause watertight (keeping it in) problems.

For me I'd know I'd be considering applying some kind of subcoat or scratch coat to the surface and then plastering. That alone on a pool that was previously plastered can run between 5K and 10K depending on the size. With this pool there would be the bonding of the scratch coat to all these different surfaces to consider, and add to the price.

Maybe it's not as bad in person as it looks in the pictures?