Sorry I'm late on this-- I'm a size 7.5 in US Women's sizes. I used a kid's size 4.5 in a workboot that I found at Payless Shoes in Tampa for around $28. I've bought several pairs of these boots and dye them/vinyl them as needed.
http://www.payless.com/boys-waterproof-boot/9599.html?dwvar_9599_color=tan#start=1 <-- these.