You should try to figure out what sells the most on Amazon or Ebay. Apparetly people are already buying it, so you'll be able to capture the ones that want to pay in BTC. I've heard people make miracles on Amazon by selling all sorts of things I'd never consider buying. But apparently there's demand...
Not really that recommendable because Amazon is only available on the US. There are people that have made fortune from Amazon but that doesn't mean that you will experience the same thing. You should find something new, something unique, and be the best at that. Surely there are already Amazon sellers that excels at a certain field of products or services.
Additionally, you can already buy on Amazon using your bitcoins by using purse.io. Personally, I haven't tried it yet but the reviews say that they are legit although the fee is quite costly.