can you be specific please because you are not and I guess not many people understand what exactly you are looking for, thus you think that nobody will help. In short, make it easy for people to help you.
For an Ebay buyer, you must look carefully to see that it ships worldwide or including asia, cannot anyhow buy & then realise seller ships to USA & Canada only. Then also use Paypal to pay. A lot more convenient.
Use VpostUSA, many seller dun send oversea. With VpostUSA (SingPost linked), seller just need to send to it USA address then VpostUSA will send back to Singapore receiver address through SingPost. Heard it's a bit ex compare to Borderlinx (same function).