What is the ruling on purchasing from a German website that sells computer parts and accepts payment via Visa, Mastercard, or PayPal with a 2.9% commission, or via bank transfer with payment of transfer fees?

It is permissible to make purchases via bank transfer, and the transfer fees are considered a wage for the bank. In the case of using covered Visa or Mastercard (pre-loaded with funds), the issuing entity is allowed to take a commission as a transfer fee. However, if the card is not covered (the bank lends to the customer), the bank is not allowed to take a percentage with each withdrawal. As for PayPal, it is permissible for the site to take a commission because it acts as an intermediary, provided that the credit card used is one of the permissible cards, meaning those that do not impose late fees or issuance fees exceeding their actual cost.