Cheapest way to ship an item internationally?

I need to ship an iPhone to a buyer on Sythe from the US to Australia. I'm unsure of what company to go through. I went on UPS's website and they quoted me 86$ which I'm pretty sure is inaccurate (I must have done something wrong). Anyone have experience with this sort of thing?

 

Were you able to input how much the package would weigh?

Furthest I've ever shipped something was from Missouri to New Jersey. I used U.S. Postal Service however and the cost was $8 (with insurance) for 1.5 pounds.

 

I mentioned it was an iPhone, which weights around 8 oz. I ended up going with USPS which cost around 5$.