I have shipping to Canada (1st class international) set up for my small item listings like cups, mugs, small bowls, spoon rests. For the larger items, they are only set up to ship within the US, but I state in my policies to contact me for a firm shipping quote on larger pieces. This may discourage some, but it also gives me the opportunity to warn international customers to be aware of taxes/fees their countries might charge. Keep in mind that any box over 12" on a side or over 4 lbs has to go Priority Mail International which is wildly expensive so be careful to keep that in mind when you set up shipping prices for big things. (someone else might know if those limitations on 1st class int have changed in the last couple years, but I don't think they have)
Yes, the shipping seems like a lot, but my Canadian customers seem already aware it will be expensive and purchase small items anyway.
I just use bubble wrap, peanuts, and single sided corrugated wrap, recycled supplies when I can. I don't double box unless it's a very expensive hard to remake item. When I run out of my current supply of bubble wrap, I'm going to look into single cell foam (think that's what it's called?) a potter friend of mine uses that is cheaper and she feels better than bubble wrap because you can use less of it to protect.