Great idea and lovely execution. If I was to give some feedback as a potential buyer:
The photo of the sock itself is a little indistinct, I don't really get the feeling that I know what the sock will be like. It's even more pronounced when viewing the mobile site, it looked like an illustration of a sock rather than a photo.
The mobile site is great (thought it was responsive at first but it's not?), but the page is not properly visible on an iPad in portrait mode, the right quarter or so cannot be accessed and the zoom facility is turned off.
There is a problem on the hyperlink to the anchor #recurly-subscribe on the buy page (when you click buy on your choice of periodicity). On some resolutions it only shows it at the bottom of the page, not the top, when you first click it. So I clicked Buy on pay quarterly, and the top of the page then showed the buy button I just clicked, and I read "2 pairs a month" - totally confused me. This was on 1680 x 1050 monitor in FF.
That's about it really. Could I ask you a couple of questions? The few times I have taken recurring payments on a credit or debit card I've found the approval rate decline rapidly over time - have you found the same? Lastly I'd love to see the packaging the socks go out in, is it branded to match the site?
Cheers, and good luck.