I have booked 2 value studios on line for next January. I guess there are none left for the dates you want, but you can call MS in case there is a problem.
They are all at Jambo so you would need to be sure you are checking Jambo. I believe if there are none available for any day of your trip, they won't even come up when you search for them.
If there are no Value Studios available for your dates, it shows all of your dates with red Xs through them. Next to that will be a link to allow you to waitlist for the entire stay.
My guess is that the OP selected Kidani Village as the resort, so no Value rooms would be displayed in the Room Type drop down since only Jambo House has Value rooms.