first of all your div
.col2-right-layout .products-grid li.item, .col2-left-layout .products-grid li.item
is not content width:300px
; it is 160px
second major problem is with your images width
it contents white space from both left and right side so it is display like this disturb alignment.
i would suggest you to remove white space or make 300px
box for product so you can adjust it in your layout.
let me know if i can help you more.