- Go "Tesla" mode: Sell directly online or manage your own distribution – Only works if you pull off a unique product, makes the pricesheet much cleaner (examples: Apple and most hardware startups).
- Use Amazon for distribution to bypass retailers and their markup: That would have worked until 2015, but on one hand it seems no seller would rely solely on Amazon for distribution (lack of foothold of Amazon?); on the other hand Amazon decided to massively dispatch counterfeited products together with merchant-originated ones, casting a doubt on the brand and tainting all their providers together.
To date, it seems like retail remains the safest way to order an item...
Sorry I don't know anything about the market. I don't even know if best buy's margin would be public information or if we'd need to make an educated guess.
Does this happen even with products "shipped from and sold by Amazon"?
Now I take the question the other way: Amazon's UI confuses the user about the third party products, which is the opposite of giving clear information about genuineness and traceability. The day it matters to them, they'll proudly say "Not a Third Party".
I suspect that Best Buy makes insignificant margins on most cellphones, but makes it up on accessories (and I guess they sell carrier plans as well?).