The cruise lines don't like to put spa prices up on websites because the prices do change according to ship/sailing date/port or sea days. The price list you received may or may not match what is actually on the ship, it is their standardized spa list with suggested prices. The prices do change and fluctuate, so don't think this list is set in stone.
Also, not all spa treatments are available on all ships. Based on what spa staff members are onboard for a particular cruise, determines what spa treatments will be available to the guests. Just because a particular treatment is listed on the price list, doesn't mean it is available. For example, while on the Majesty OTS in early 2007, they had a haircut/close shave/head and shoulder massage special for men only for about $75. When I sailed on the Vision OTS in late 2007, I went to the spa to book that same special because I saw it in the standard spa flyer in our cabin, but I was told they couldn't because the spa staff member that did this particular treatment wasn't onboard for the sailing.
The Spa also will give specials and discounts while in port for those willing to stay onboard, and the prices go back up during sea days.
I will be sailing on the Adventure OTS 2 weeks after you depart, really looking forward to the cruise!