Surface mail, but that will probably take 6 weeks.
If you are going to order atleast a 21KG package usually sellers use DHL for free
Usually there's a minimum weight charge or a base charge.
If you want to ship with well known service provider like DHL, FedEx or Ups, you can open a corporate account and negotiate a discount rate. You can do this in your own country, doesn't matter shipment origin and destination
I buy some stuff from China and so far the cheapest is china post but it takes around 14 days to reach Indonesia. EMS is my favorites since they only take 7-10 days to reach my house.
If you only send small package I think what benzy suggested is probably the best option you have. it will be different if you ship lots of stuff at once.