You may want to keep an eye on Beverly Hills Car Club. They typically have several DeLoreans for sale at any given time that are barn find cars in rough mechanical shape.
https://www.beverlyhillscarclub.com/...l=%5BDMC-12%5D
They only have one car for sale right now and it's a complete disaster, but they have had cars in the past that might meet your needs.
The ideal situation in your case would be to find a dusty car that has been tucked away in someone's shed for two decades and has recently been pulled out to be sold. The mechanical systems would basically need everything so that would drive the price way down. That would be perfect in your case since you want a non-runner.
Barn find cars usually have some of the best interiors since they have been hidden away in the dark somewhere to protect from sun damage. The exterior stainless on most cars can be cleaned up with a little elbow grease and a scotch brite pad. Worst case you'd need some paint on the fascias and SEM Trim black on the other pieces.
If you're looking for a car in the sub-15k range for cosmetic display only, a fresh car right out of the barn will probably be your best bet. That's my 2c at least.
