function wc_subscriptions_custom_price_string( $pricestring ) {
global $product;

$products_to_change = array( 170, 215, 312 );

if ( in_array( $product->id, $products_to_change ) ) {

    $pricestring =  'Current year dues are ' . wc_price( $product->subscription_sign_up_fee ) .
        ', with recurring annual dues of ' . wc_price( $product->subscription_price );
}

return $pricestring;
}

add_filter( 'woocommerce_subscription_price_string', 'wc_subscriptions_custom_price_string', 10, 3 );
add_filter( 'woocommerce_subscriptions_product_price_string', 'wc_subscriptions_custom_price_string', 10, 3 );