I think you should get a professional customized painter, Few months back, I was in the same situation for my own warehouse and I took help from a customized art company that reviewed my warehouse and created 6-8 different diamond paintings in different positions. Now my warehouse looks complete...
I've always questioned whether it was really a negotiation gimmick. Would they drop the price if you proposed the equine discount during a price negotiation? Or do they simply factor it into the regular negotiation discounts.