They usually have some small bottles of cond. shampoo & hand lotion in the bathroom shower area where the saunas are located-- I still prefer my own but it is a way to cut down on packing if you are not fussy. You can also buy what you need on board in small sizes if you don't need a large variety...or at inflated prices in the salon!
I'm with Donna. I always bring my own. My hair being curley gets frizzy enough I don't want to try to use new shampoo/conditioner especially on vacation. It doesn't bother some people's hair but I'm not taking the chance. It's your own choice.