I'm a US citizen in Singapore.
Detlof nails it on the head. Wire transfers are commonplace for even consumer transactions outside the US. The reluctance of US sellers to use them is due to having to release the bank name, your account number, and address to the seller.
However, since this is the #1 means of transferring money in commercial transactions for the last 90 years with trillions(yes) of dollars being transferred every week, you can take it as a given that it is perfectly safe. Usually the funds will be in your account by end of day and you can then ship.
BAX global is the best, from the viewpoint of the buyer as the cost is half or less as compared to UPS. If the buyer is willing to pick up at the airport, the charges can be halved again.
A typical power amp will cost $300 to ship from the US to Hong Kong or Singapore by UPS; about half that by Bax Global, and less than $100 if the buyer is willing to pick up at the airport.
All the buyer has to do is to click on the shipping link on the ad, which will take him to the BAX site.
Of course, there are other companies too, such as Cox and Kings etc.