I just returned from the Viking River Cruise Cultural Delights April 29 cruisetour on the Viking Century Sun. To clear up the laundry issue, the prices are in Chinese Yuan (or Renminbi). So an item listed at 25 is about $3.27 and an item listed at 35 is about $4.58 (using an exchange rate of 7.65 Yuan to the U.S. Dollar). So yes, laundry aboard ship is pricey. The suggestion to pack everything you need is problematic given the the weight restrictions on the 2 intra-China flights (between Beijing and Xian and Xian and Chingqing) of one checked bag per person with about a 44 pound limit!
An alternative to laundry is to bring hand washable items that can dry in the bathroom on the ship.