Recharges of German prepaid SIM cards from abroad and by foreigners finally possible
 

Aufladen.de, a reseller of recharge vouchers, recently started accepting PayPal which finally allows foreigners to buy from them. Before they accepted credit cards but only if issued by a German bank.

PayPal payments are subject to a an additional fee of € 0,50 on top of the face value of the topup voucher.

Recharge codes will be displayed and also sent by email immediately after purchase which you need to enter according to your provider's instructions. Lidl and Fonic customers can enter recharge codes online on the customer portal by the way.

The service is run by a Dutch company which offers the same thing for the Netherlands at http://www.opwaarderen.nl/ which allowed me to recharge my Dutch T-Mobile SIM card using PayPal. Before they only accepted Dutch credit cards for payments on the Dutch platform.

Actually, cabox.de already offered recharges with PayPal for a few years. I even used them once. But recently the site went offline...

I tried this recently using my US credit card and Paypal account and received an error each way.

However, as my goal was to get a Vodafone topup for my Vodafone UK SIM (you can apply topups from other Vodafone countries to the UK SIM), I instead went to the Dutch site you mentioned and was able to obtain a Dutch topup to apply to my UK Vodafone SIM.