edd_get_variable_prices()

This function will return an array of all of the variable prices set for the provided download ID.

$prices = edd_get_variable_prices( $download_id );
if( $prices ) {
	foreach( $prices as $price_id => $price ) {
		// $price['name'] is the name of the price
		// $price['amount'] is the amount of the price
	}
}