You can make any plan expensive regardless of type of phone; it all depends on your monthly data allotment, how often you want to upgrade your phone and additional services/features.

An AT&T 15gb plan with unlimited calls/texts is $115/month.

Next 12 (upgrade every 12 months) you pay like $40-45/month for an iPhone 6s. They recommend insurance which is another $8-11/month. Tethering adds $50-65/month.

My wife paid $203/month for ATT service before I switched her to Cricket. Now we pay $35/month. Same phone same network...