The Disney Magic Laudry rooms are all about a system, that is for sure. I was lucky and had someone tell me the ins' and outs' of the machines.......
The washer is $1.00 as is the dryers, and depending on the cycle you choose on the dryers and what floor you are on is the time you get for your money. On the 7th floor room you get more time than the 6th floor, why it is beyond me. Also if you want more time - you just add one quarter at a time - push the cycle button and it will add the minutes, you do not need to add another dollar is quarters.
I brough my own detergent, but seem to remember that it was .75 and there are change machines there. The washer and dryer do not take bills.
Also, the room on the 7th deck has an iron and ironing board.
I would suggest that when you have items in the dryer that you are there when they are supposed to be done, because I witnessed so many just empting the machines and tossing their items in and leaving - it really was terrible.
All in all it sure beats packing dirty underwear, socks and bathing suits!!!
Have a "MAGICal" Cruise!!!!