International Primary Schools (Istanbul)

Hi, my husband and I are looking into moving to Istanbul (his family is there). We love the city and think it will be great exposure for our kids :) My oldest is 5 and will be entering Kindergarten...she speaks a little Turkish, but we would like to send her to an international English speaking school at least at first until she is transitioned...researching online, these schools are VERY expensive ($ Protected content per yer, per child). Are there any mid-priced international schools? Not sure we can afford two tuitions....plus all the extra fees that are added. Advice???
Thanks! As soon as my husband finds a job, we are packing our bags!!!