omasou
The upgrade plans aren't worth the time or trouble. Especially, carrier plans that extend the period to 36 mo.
I gave up on eBay b/c of the scammers and Trade In companies that try to lower the value of the phone after they receive it. Either way too much hassle.
What I do...
I have an iPhone 13 Pro that I purchased last year from Apple on their 24 mo 0% payment plan. The remaining balance that I paid off was $424.
$ 999 iPhone 14 Pro
$ -600 iPhone 13 Pro Apple Trade In value
$ 399 net cost plan to pay in full
$ 399 + tax = $424
So for a $ 424 each year I have a new top of the line phone, no monthly commitment and less hassle in my life. The same can be accomplished using a monthly plan but is more complicated b/c you need to pay off the previous iPhone.
Either way a new phone works out to
~ 1/3 MSRP when kept for 1 year
~ 2/3 MSRP when kept for 2 years
Purchase AppleCare or not, but NOT a requirement. Cost is similar or less than carriers and I would rather deal w/Apple than a carrier. https://www.apple.com/support/products/iphone/