Hii Margaret from my experience laundry service in tel aviv cost around 60 nis per 6 kg that is what they all usually take. you can find cheaper ones but not in the same quality.
I usually use this service they charge 60 nis as min of order they come fast to pickup and to drop off and they do dry cleaning as well.
here's their number +972-584-688-585 and their website
Welcome to your first post on the Israel forum--recommending a laundry to someone who asked 7 months ago!!! Stick around if you enjoy posting and add some "real" information. New faces are always welcome.