You do not need US$'s. Simply pay by check, you can easily mark it to denote that the amount of money has to be paid in US$'s. There usually is space for a currency sign like USD i\on a check. Your bank will take care of all hassle and charge you in your local currency. But make sure to ask them first what they will charge for their work!
Alternatively go to a bank or post office and get an international 'money order'. This will be made out in U.S. dollars, and all banks should be able to give you an international money order for this. You'll be able to pay in your local currency.