Navy pinafore dresses - or "jumper dresses" as they say in the US

So, I've been looking for a navy pinafore dress, preferably in cotton not polyester, that would be acceptable as school uniform. When looking for these, it's good to know that on American web sites the pinnies are often called "jumper dresses".

I'm way too stingy to pay for shipping from the states, but here are some cute "Jumpers" I've found:

Girls cord jumper dress (navy, cotton) for £50.29 
http://www.jcrew.com/girls_category/dresses/everyday/PRDOVR~04179/04179.jsp
OMG Free shipping to the UK! But still pretty expensive.

Same company, about the same price category
Girl's poplin origami bow dress, navy, cotton £57.48
http://www.jcrew.com/girls_category/dresses/party/PRDOVR~02997/02997.jsp

Another one from J. Crew. I want to buy the entire lot. Could they just be a bit cheaper, please?
Girl's ponte shift dress, navy, cotton £46,49
http://www.jcrew.com/girls_feature/schooluniformshop/UniformSkirtsDresses/PRDOVR~05172/05172.jsp?color_name=navy