I have heard that the laundry price can vary a little depending on where/when you are cruising. Generally I have heard higher prices when cruising in Europe.
As you are stuffing your bag for the laundry. Make sure you write down an inventory so you can confirm that you get everything back.
When I stuff a bag full of laundry, I put everything into piles - socks, underwear, t-shirts, golf shirts, shorts, etc. etc. and then I count each pile, mark it off on the inventory sheet that comes with the bag, before stuffing the clothes into the bag. Sometimes I even double check the amount before putting it into the bag.
If there isn't an inventory sheet with the bag, ask your cabin steward for one. You must fill it out and sign it. Unless the steward is in the room for me to give him the bag, I just leave it on the bed or sofa with the inventory sheet laying on top of the bag. DO NOT forget to keep one copy for yourself.
I love it when someone else does my laundry on the cruise - do enough of that at home.