Infinite Scroll plugin on Ebuy theme

The page that you have mentioned above has the following markup

<div id="content">
<div class="box " id="post-302"></div>
<div class="box " id="post-298"></div>  
<div class="box lastbox" id="post-296"></div>   
<div class="box " id="post-293"></div>      
<div class="box " id="post-265"></div>
<div class="box lastbox" id="post-259">

        <div id="navigation">
        <div class="alignleft"><a href="http://soballer.com/product/accessories/page/2/">« Older Entries</a></div>
        <div class="alignright"></div>
        <div class="clear"></div>
        </div>
</div>

Try these:

content selector -- #content
nav selector -- .alignleft
next selector -- .alignleft a
item selector -- .box