Want to sell via Paypal or Amazon and offer Etsy link

So I’ve got a couple of different E-books that I want to sell on my blog and I’m wondering if anyone has tried all three of these routes before. The Etsy one is probably just going to be as simple as me putting a link on there saying “buy on Etsy,” but I’m wondering if there is a good add-on that will allow me to accept both PayPal and Amazon payments?

Leaning toward Ready! Ecommerce, but I don’t see any Amazon payment option on there. I haven’t picked a theme or anything for my site yet, so I thought the ordering system would be the best thing to start with.

Thanks in advance!