protected $_product;

public function __construct(
    ...
    MagentoCatalogModelProductFactory $productFactory,
    ...
) {
    $this->productFactory = $productFactory;
}

public function getPriceById($id)
{
    //$id = '21'; //Product ID
    $product = $this->productFactory->create();
    $productPriceById = $product->load($id);
    return $productPriceById;
}

public function getPriceBySku($sku)
{
    //$sku = 'testing'; //Product sku
    $product = $this->productFactory->create();
    $productPriceBySku = $product->loadByAttribute('sku', $sku);
    return $productPriceBySku;
}

<?php

    $productId = 8 //product id

    $objectManager = MagentoFrameworkAppObjectManager::getInstance();
    $productRepository  = $objectManager->get('MagentoCatalogApiProductRepositoryInterface');
    $product = $productRepository->getById($productId);


    $abstractProductBlock = $block->getLayout()->createBlock('MagentoCatalogBlockProductAbstractProduct');
    echo $price =$abstractProductBlock->getProductPrice($product);


?>