>>qainsi+(OP)
We have an Amazon-branded Chase card that gets 2% back on Amazon purchases if you're not a Prime member. There's no annual fee for the card.
If you are a Prime member, it's 5% back. $139 is the annual fee for Prime. $139/3% difference = $4633.33
Somewhat to my surprise, we spent about $3700 on Amazon this past year, meaning $139-$111 or Amazon Prime cost us $28.
>>jdeibe+bh
I have also seen purchases on this card bump to 6% if you choose the no rush shipping option (which realisitically is the same as standard anyway...)