Change WooCommerce price display with a custom field

wc-change-price-display-custom-field.php

<?php
// only copy the opening php tag if needed
// Change the shop / product prices if a unit_price is set
function sv_change_product_html( $price_html, $product ) {

	$unit_price = get_post_meta( $product->id, 'unit_price', true );

	if ( ! empty( $unit_price ) ) {
		$price_html = '<span class="amount">' . wc_price( $unit_price ) . ' per kg</span>';	
	}
	
	return $price_html;
}
add_filter( 'woocommerce_get_price_html', 'sv_change_product_html', 10, 2 );


// Change the cart prices if a unit_price is set
function sv_change_product_price_cart( $price, $cart_item, $cart_item_key ) {

	$unit_price = get_post_meta( $cart_item['product_id'], 'unit_price', true );

	if ( ! empty( $unit_price ) ) {
		$price = wc_price( $unit_price ) . ' per kg';	
	}

	return $price;
}	
add_filter( 'woocommerce_cart_item_price', 'sv_change_product_price_cart', 10, 3 );