Hotel laundry services of any kind are unbelievably expensive in my experience. Usually US$10-30 per item, or the local equivalent, with e.g. socks and underwear being at the low end, slacks and collared shirts at the high end. Dry cleaning, of course, is a significant premium beyond that.

I thought it was just a US thing when I was younger, but I've found it to be true even in other countries.