Unfortunately, any mode of payment is NOT totally safe!! The most unsafe one is by cash, bank TT is also high on the unsafe list. Personally I perfer Paypal.
Actually, it's not the mode of payment that one should worry about, but to whom you are paying is critical. Check the seller's record carefully before you bid his stuff. email the seller about the exact ship' (& handling) charge before bidding.
SH charge via normal airmail from US to SG for small item is typically USD15 - 20. Some even charge USD30 or more. Unless you are looking for something really rare or you have a bargain, not worth to buy from eBay IMHO.