I am currently struggling with amazon right now. I decided to start with Amazon instead of eBay.
first off, it's $40 a month. HUGE competition, i can't list anything that won't be outed.
You have to use Fulfilled by Amazon, which is a very good concept, but is the very thing that is screwing me over. $1 per order shipped, and $1 S&H. You also have to account for the price you're listing for (which is already discount), and you have to beat that to win the "buy box", which is the main page for the item. With all that accounted for, I was losing money each sale because of the small fees that killed my profits.
On top of that, all your money is held for 2 weeks, so everytime they bill your account $40 a month, for JUST the account, it basically took the money that i've been making, and now i'm left with $1.86. Forgot to mention that they have a comission on each item you sell (around 15%)
Just to put this in perspective:
Gross sales (in the past week): $110
Promo rebates: -3.89
Amazon fees: -69.99
Sub Total : 49.92
FBA fees: -8.00
Subscription fees: -39.99
Total balance: $1.93
You have to basically buy rock bottom prices from manufacturers i think, to win on Amazon.