I’m talking about the unlocked iPhones. Because I don’t think the carrier promotions are “cheap” in the sense they usually make the money back from the monthly fees, and then more.
I can think of a few places, some are probably cheaper, but I am not 100% sure about the quality (especially the battery life for the refurbished iPhones). Below are the two places that I trust.
New iPhones at Apple, SE and 14 are two cheaper choices. Personally I think 15 or 16 are probably the better deals.
If one has the Chase sapphire or freedom credit cards and has some Ultimate Rewards (UR) points to spare, from time to time they have promotions for Apple products in the redemption center. It’s another way to get brand new iPhone. Note this may not be the most cost effective way to burn the UR points. But if they do promotion: it means 1 point is worth 1.25 cent during the redemption. If you travel, and could use the UR points, try to use the points there as 1 point is usually worth 2 cents or more there.
Personally I have used UR points for a few iPhones in last few years.
Refurbished
In the order of quality guarantee (top to bottom).
Refurbished iPhone at Apple: it seems they don’t have a lot of iPhones in stock now. Most are the larger or pro models (which are usually more expensive).
Other two places I am aware of refurbished iPhone: eBay and Amazon.
This somewhat reminds me of the preowned certified Toyotas I bought in year 2013 and year 2022.
Insurance
Do we need insurance? I usually insure it by myself (you may read this post if you have some time). Personally if I need insurance: I would buy from Apple instead of the carrier.
But this again reminds me of the one time I bought the “extended warranty” for my 2012 Toyota Sienna (preowned certified) from the dealer. Most of those are not necessary. In the case of iPhone, no pun intended, buy a good case from Amazon is probably the only insurance you need.