Payment can be done in advance by bank transfer, PayPal or credit cards. Paying with PayPal and credit cards will normally cost a credit card fee.
The seller's conditions of payment are stated on the invoice. If payment is made after its due date the seller reserves the right to charge interests and fees on balances as stated on the invoice from the due date until payment is made. Payments shall always be used to settle due interests and fees on outstanding balances first and hereafter the debts.
The buyer is not entitled to set off any counterclaim against the seller unless specifically approved in writing by the seller. The buyer has no right to withhold any of the payment because of counterclaims of any kind.
In the case of delayed delivery due to the buyer's circumstances the buyer is obliged to pay the seller as if there had been no delay, unless otherwise explicitly authorized by the seller in writing.