What about something with Amazon

Basically, people could buy anything from Amazon but within your site. Not sure how to implement the idea. Maybe using services like BitPay.
You could make a clone from Amazon website, people buy items (delivered by Amazon) and pay in cryptos. The coins are converted to fiat automatically (with Bitpay or any other) and your Amazon account is automatically topped up with a bank account (the one you used to receive BitPay payments)