I bale my own but a neighbor bales for others. I think last year he charged $15.00 per bale. That is cut, raked and rolled in to 4 X 5 bales string tied. Actually thought about having him do some of mine because I figure it costs me almost that if I don't count my time.
I think it sound reasonable but I don't think I would pay to have it stacked unless I did not have away to do it myself. Just make sure it is someone you can trust to make a tight full sized bale. I have heard of people loosening up a baler to make more bales.