You can "purchase" free ebooks from Amazon as long as you have registered a valid credit card
or gift card.
So:
Get Kindle through friend.
Get cheapest possible Amazon gift card through friend.
Call amazon and have them manually register your Kindle to your free account.
Add gift card to amazon account.
Purchase free books on the Amazon website, and download them from
http://amzn.com/manageyourkindle for your device.
Sideload the books via USB to your device.
If you want to get complicated, it should be possible to make use of the USBNetwork hack to tunnel the Kindle's internet connection over USB through your PC, so you can even connect the Kindle to the wired internet. Might be preferable anyway, since the Kindle does not download as much information to access the Kindle store as the main website takes up.