I was at the YC in December, doing laundry! I used the one by the quiet pool, where I relaxed in the hot tub between loads. I was in the hot tub illegaly, after hours, but we won't go into that! (It really was the highlight of my trip. Alone in the hot tub. Totally alone... aaahhhh!)
As the previous poster mentioned, each load is $2. The soaps and fabric softeners are $1 per single load "serving". I had to go to a grocery bstore outsdide of the world - Goodings, I think - to get some medicine for my DD, and it occured to me to pick up a small bottle of detergent. It cost me like $3.50, and I did more than 4 loads! I just left what I didn't use on the counter in the laundry room...
Wow, you're going for a long stay, huh?