Considering that the Vox requires it's own charger and Kobo is no longer selling replacement chargers, I would not, at this point, purchase a Vox.
http://www.kobo.com/charger-ca.html
I have my Vox that I got nearly a year ago. The charger started to fray after less than 2 months. Kobo did send me a new one at no cost to me after I started a support ticket. At that point they weren't selling chargers, but they later started to do so. However, as you can see at the above link, they are 'out of stock' and they have been for quite some time now. I don't expect them to stock any more, since the Vox is likely going to be obsolete. I think Kobo is now handling issues with the charger on a case-by-case basis, as I've seen at the getsatisfaction web site.
https://getsatisfaction.com/kobo