I calculated the cost for a Mobile Share Flex 10GB AT&T Plan and getting two iPhone XS Max 64GB.
It comes out to be $183.15/month + tax/fees.
($154 tax & $60 activation fee, $85 base plan + $40 device access fee + $73 phone fee - $23 credit)
Total cost of this AT&T BOGO "deal" is $5,861 ($6,561 - $700 credit)
For comparison, you can get 2 lines of AT&T Prepaid (6GB each) for $70/month or $2,240 for 32 months.
Including the full cost of the phones: 2 x $1,099 + $154 tax = $2,352
Total cost for 2 equivalent AT&T Prepaid lines and full price phones for 32 months = $4,592
Which is $1,089 cheaper than this "deal".
First, you're assuming postpaid and prepaid are identical services on AT&T.
They're not. Mobile Share Flex provides benefits such as HD voice, Wifi calling, and other stuff. More info here
https://forums.att.com/t5/Network-C...tween-postpaid-and-prepaid-plans/td-p/5467474
Whether the additional abilities make a difference to someone is up to them, my intent is just to point out that the two are NOT equivalent services.
As to your numbers -- no need to go to 32 months, AT&T normally backfills the initial credits in month two or three. By the time you hit the end of the term you're done.
So for a 30 month term we have:
Postpaid service: $60 activation plus $125/mo service (not incl tax/fees), total $3810. Phone cost $2198+tax less $700, total $1498. Grand total $5308 (plus phonesales tax). (I think you're adding in the Next phone fees for two extra months after they're paid off)
Prepaid service: $70/mo service (not incl tax/fees), total $2100. Phone cost $2198+tax. Grand total $4298 (plus phone sales tax).
Difference is $1010, or $16.83 per line per month over 30 months. How important the stuff like HD voice, wifi calling, roaming onto non-AT&T towers, etc is will depend on the person.
This also assumes someone doesn't have a FAN discount from work or their school, cutting the price of the Mobile Share Flex plan. In my case with a 20% discount, the mobile share flex plan cost is reduced by $17/mo bringing the total difference to $500 rather than $1010.
Question - how well does a cellular Apple Watch do with AT&T Prepaid? Can you get your phone's calls on the watch when you're not near the phone?