Cost of shipping two pairs of shoes from the US to the UK?

[ruffin51]

I have not sold any shoes in a while and I am working on a potential deal to ship two pairs of size 13 runners from the US to the UK. I have always used USPS EMS to ship overseas. Are there better/cheaper options? What would you estimate the cost for shipping two pairs to the UK would be, and is it a better idea to use a flat rate box or not?

Thank you in advance!