cargar un texto deacuerdo a la seleccion de un combo

[alfil123]

este es el codigo que uso para cargar el combo



function build_select_with_ajax_loader($select_id,$value_ar ray,$javascript_handler_fn,$javascript_handler_fn_ extra_params,$server_handler_fn,$loader_image)
{
$string = '';
$string .= '<table border = \'0\'><tr><td>';
$string .= '<select id = \''.$select_id.'\' name = \''.$select_id.'\' onChange = \'if(this.value != ""){call_ajax_request(this,"'.$javascript_handler_ fn.'","'.$server_handler_fn.'",'.$javascript_handl er_fn_extra_params.')}else{handle_function("'.$jav ascript_handler_fn.'_reset")}\'>';

$string .='<option value = \'\'>Please Select</option>';
foreach($value_array as $main_key => $main_value){
foreach ($main_value as $key => $value) {
$string .='<option value = \''.$key.'\'>'.$value.'</option>';
}}
$string .='</select>';
$string .='</td><td>';
$string .='<img style = "display: none" id = "'.$select_id.'_loadimg" name = "'.$select_id.'_loadimg" src = "'.$loader_image.'">';

$string .='</td></tr></table>';
return $string;
}

donde recupero el precio para mostrarlo