Article courtesy of The Wall Street Journal, written by Joanna Stern.
There are three things to remember when iPhone shopping:
1) The next iPhone will always be better than the current one.
2) No matter the season, Apple will always try to sell you an iPhone.
3) The next iPhones usually come out in September, at which point prices on at least some current iPhones will drop.
Add it all up and you get my patented iPhone No-Buy Rule™: Do not buy an iPhone once June rolls around. Wait for the new one.