With my insurance, my copay is $30 a month, regardless of the dose ($30 copay for the Crohn's starter kit of 6 pens, $30 copay for the box with 2 pens). My GI doctor's nurse recommended signing up for the Humira Protection Plan when we first decided to give Humira a try...I had to wait awhile to get the card, but now I only play $5 a month ($30 copay, $25 of that paid through the protection plan).
I still had to jump through hoops to get it approved through my insurance, though (they kind of had to approve it, since I've been on pretty much everything other than the other TNF-blockers).