As you might have noticed from the
Lidl mobile thread, I favour Lidl over Fonic due to the cheaper and better data tariffs. Except for data tariffs Lidl and Fonic are nearly identical in all other aspects since Lidl is a rebranded product actually offered by the same company (Fonic GmbH).
However in contrast to Fonic Lidl accept PayPal and credit cards for online orders, so this might also be an option:
Lidl Mobile Starterpaket - Lidl Deutschland - lidl.de
Unfortunately they don't ship outside Germany.