There's a dollar(sign) in variable name

You could try:

PHP Code:

$tmpVar = 'prince_in_u$';
echo 'Price in US: ' . $comp_prod->$tmpVar; 


Or

PHP Code:

echo 'Price in US: ' . $comp_prod->{'prince_in_u$'}; 


Another idea would be to fetch the result as an array instead of an object.

PHP Code:

foreach ($query->result_array() as $row)
{
   echo 'Price in US: '. $row['prince_in_u$'];
} 


Or as a last resort you could change the column name in your database.

PS, in your code you forgot the dot sign to concatenate the string and the object.