Form

<form method="get" id="searchform" action="<?php echo home_url(); ?>">
    <input type="text" onclick="this.value='';" onfocus="this.select()" onblur="this.value=!this.value?'Product Search...':this.value;" value="Product Search..." name="s" id="s" class="left" />
    <input type="image" src="<?php bloginfo('template_directory') ?>/images/icosearch.png" id="searchsubmit" value=""/>
    <?php
        wp_dropdown_categories(
            array(
                'child_of' => 426,
                'class' => 'styled',
                'id' => 'make',
                'name' => 'make',
                'show_option_all' => 'Make...',
                'taxonomy' => 'product_cat',
                'walker' => new dropdown
            ))
    ?>
    <?php
        wp_dropdown_categories(
            array(
                'child_of' => 427,
                'class' => 'styled',
                'id' => 'model',
                'name' => 'model',
                'show_option_all' => 'Model...',
                'taxonomy' => 'product_cat',
                'walker' => new dropdown
            ))
    ?>
</form>