They won't hurt in the store unless they are a terrible fit. This is where you have a problem with shopping , at big boxes like Costco. Like others, I am impressed with the value of a wide variety of products I have bought there. But there is no customer service. Your boot should fit snugly, especially in the heel area, with more room in front of the toes. Be sure you are wearing the right socks....

That is an insanely cheap price, but boots are hugely important, so it might be worthwhile and go to a specialized outlet, like REI,where you can get help in fitting.

OM, I once hiked fifteen miles in my steel toed work boots. The key word in that phrase is 'once.' Never again!