Possible purchase...How bad is this delamination? (pic)

X3. That rear picture means the rig is ready for one trip -- to the scrapyard. Mold is going to be an issue, the delamination already has made the rig's value just worth the metal in it, and there is no way to fix that in any reasonable way, unless you want demolish the outside and reuse the frame/chassis, building from scratch on top of it.

You can find far better for $8000 or lower. It will take some looking.