You have a mixture of trying to handle multiple rows returned, a single row returned, and only god knows what. So.... I would recommend:
mysql_result($query, $x, "ID");
include 'php/opendb.php';
echo $skuid;
echo $dbrow;
mysql_select_db("brownells_api_data") or die(mysql_error());
$query = "SELECT * FROM Ammunition WHERE $dbrow = $skuid" or die(mysql_error());
$sql = mysql_query($query);
// You Do Not Need this row
// $row = mysql_fetch_array($sql);
$prodimg = mysql_result($query, $x, "Thumbnail Image");
echo mysql_result($query, $x, "Thumbnail Image");
echo "<div class=toparea>";
echo "<div class=imgarea>";
echo "$prodimg";
echo "</div>";
echo "</div>";
echo mysql_result($query, $x, "Description");
echo 'hello';