If you buy a G-Shock internationally, the best way to pay the seller is by Paypal. Even in the Netherlands, Paypal is much faster than most bank-transactions. In this case the seller pays the Fees, so the fees are mostly calculated in the end price or the shipping and handling.
Some U.S. sellers prefer Bidpay for international transactions. Bidpay sends a Western Union cheque to the seller. Here the buyer pays the the fee and the postage. This transaction is relative slow, but the seller gets a conformation that the cheque is sent out.
If the seller doesn't have a Paypal or Bidpay account there are still two options:
Sent the money in a shielded envelope or transfer the money with international banking. I use both methods for paying from the Netherlands to Germany, the U.K., France and Belgium. Both methods take about four working days.
For small amounts of money I use the first method. I put the banknotes between a postcard and aluminum foil. That way the money is not detectable. I normally use priority mail, but with larger amounts of money I use registered and insured mail.
For larger amounts I also use international banking. This also takes four days, which I think is very slow, and it is also very expensive. If you can get someone's IBAN-number, which that person probably don't know, the transaction costs start at 6 Euro, which is much more expensive than insured and registered mail. The only advantage is that I can pay at home, and do not need to go to the post office.