I think that is the equipment and support facilities in totality. There were huge amounts of equipment just left there without even a thermite charge dropped into them. Not just tanks. Everything down to and including SAWs, shoulder fired missiles, etc.
I believe that would add up much quicker than you think it would.
I personally had not given the $85 billion assertion much thought in detail until I read your post, but as you opined accurately, it can't be just equipment.
Good call! (It made me think about it)