the cost also depends how much $$$ the airline wants. i haven't seen high pricing of wifi on Alaska like I do on Delta.
Also - when you guys have slow connections - click on live chat and ..... about it. i did today flying SEA-JNU and they gave me a $15 credit. The towers in British Columbia must be hurting because I've never had such a slow slow SLOW experience and I'm used to Chicago/Dallas/Atlanta being uber slow.