Best Place to Sell Digital Products From

Hi, I have a client with many digital product for download. They are currently stored on his localwebhost. I am looking for a solution that is compatible with both Cart66 and WOO because...
-He only wants to have to upload products to one location.
-It needs to be a secure location with secure links
-It need to be an affordable solution (I think the product sizes are 8gig of zips right now)
-It need to be compatible with both Cart66 and WOO to pull from securely

So I'm thinking of Amazon S3, is this the best solution? Or does someone have another please?