The last of the Parker Repros sold for $1,999/2,099. Let's not jump to conclusions regarding appreciation. The law of supply and demand will dictate future value. Currently, the supply of RBL's is plentiful. Once (if) that changes, the price will soar.
By the way, Replacement, you will love your RBL-28. It's the best. I have one with 30" bbls., DT, ES, BTFE, choked Skeet/IC and it's my favorite. I've added a .6" decelerator pad and it weighs 5lbs., 14oz......perfection.