美國是算磅的 1lb=0.454(?) kg
you got three chooses
1. express mail (the most expensive, 2 days)
2. priority mail(less expensive, 3-5 days)
3. parcel post(the cheapest, one week)
4. by sea....(it will take 4-6 weeks)

http://ircalc.usps.gov/default.asp?...ingle&CID=10418
you can caculate your post here.
normally the post cost is cheaper than it in Taiwan