from-price-suffix.php

<?php

/**
 * Change price format from range to "From:"
 *
 * @param float  $price
 * @param object $product
 *
 * @return string
 */
function iconic_variable_price_format( $price, $product ) {
	$suffix = sprintf( '%s ', __( '+', 'iconic' ) );

	$min_price_regular = $product->get_variation_regular_price( 'min', true );
	$min_price_sale    = $product->get_variation_sale_price( 'min', true );
	$max_price         = $product->get_variation_price( 'max', true );
	$min_price         = $product->get_variation_price( 'min', true );

	$price = ( $min_price_sale == $min_price_regular ) ?
		wc_price( $min_price_regular ) :
		'<del>' . wc_price( $min_price_regular ) . '</del>' . '<ins>' . wc_price( $min_price_sale ) . '</ins>';

	return ( $min_price == $max_price ) ?
		$price :
		sprintf( '%s%s', $price, $suffix );
}

add_filter( 'woocommerce_variable_sale_price_html', 'iconic_variable_price_format', 10, 2 );
add_filter( 'woocommerce_variable_price_html', 'iconic_variable_price_format', 10, 2 );