According to www.usinflationcalculator.com, 500$ would be ~780$ in modern money. Close to the price of the base iPhone 17 and 300+ dollars difference when compared to the smaller of the pro models. So I suppose its price stability is based on the target you pick. If it were me, I'd target against the 1000$ iPhone Air.
1:My personal iPhone 1 never saw an att sim. It was purchased at an apple store.
2:https://techcrunch.com/2008/06/09/3g-iphone-comes-with-2-yea...
I meant a contracted subsidy where the user sticks with att or whatever for $n$ years.
At 2% inflation prices increase by 40% every 17 years, and it takes 35 years for them to double. At 3% (closer to real inflation), prices would double every 23 years: 1.03**23 = 1.97...