It should fall-through to e-junkie's traditional non-Javascript cart hosted offsite. I personally think the experience is decidedly suboptimal next to either of the JS carts but, honestly, I think the Internet is moving away from assuming that Javascript is optional.

(I would have a different opinion if I had to support a range of mobile browsers but, well, I sell downloadable software to elementary schoolteachers. Most of them don't think "Ooh great I loved this downloadable free trial! Let me write down the URL, get out my iPhone, type in the URL, then order a copy!")