If that is what USPS said that is what you would have been quoted if you asked for a quote. Again our site does not calculate the item weight and produce a real time shipping quote yet so the only way to get an accurate quote is to email us. For outside the US 48 or anywhere for that matter if the shipping seems outside the norm then it probably is. Our site is not yet smart enough to deal with every shipping situation that comes up. It is more based on a flat rate table at this point. We are hoping to revamp the entire site this spring and summer.
I'm sure you've probably looked into it, but I was just googling some html shipping calculators and USPS had something that may or may not work for you. https://www.usps.com/business/web-tools-apis/welcome.htm