The process to make fine offset printing paper is relatively fast. A typical mill will run their machines at about 1500 to 3000 feet per minute. When cast or resin coating an ink jet sheet, the coater runs at a whopping 100-400 feet per minute. Look for these prices to fall steadily as time goes on. That's how they keep their giant 50,000 person monsters afloat.
Red River takes a far smaller mark-up as can be seen by comparing prices.
Uncoated art papers like Concord are priced high because 3rd and 4th party vendors are selling them. Make t hree to four mark-ups from the mill to the customer and you have high prices. Again, Red River tries to keep that to a minimum by having one mark-up only from the mill to the customer. Coated art papers are going to continue to be high because they are hard to make and are used for high-end printing. A Mercedes will always cost more than a Honda for the exact same reason.