This is just a post, in case anyone's searching for reviews of s2Member payment processing plugin.
If you have any kind of media like videos you plan to make available on your site for members-only, s2member is a pretty solid plugin, and it's very well developed and easy to use. That said, if you have anything above 3 or 4 megs, you will NEED to buy Amazon s3 storage. Period. There's no other way. I just had a nightmarish week and a half dealing with this plugin, not using Amazon. It wasn't made clear that I'd run into that issue when I first made the purchase, and since you HAVE to purchase the plugin before you can read the forums, you won't know until it's too late. And, if you're already paying for hosting, and you don't want to have to add this additional cost, you'll need to take a closer look at some other solutions.