Change the way WooCommerce variable product prices are shown: http://calebburks.com/modify-variable-product-prices-in-woocommerce

wc-ninja-variable-product-price.php

function wc_ninja_custom_variable_price( $price, $product ) {
    // Main Price
    $prices = array( $product->get_variation_price( 'min', true ), $product->get_variation_price( 'max', true ) );
    $price = $prices[0] !== $prices[1] ? sprintf( __( 'From: %1$s', 'woocommerce' ), wc_price( $prices[0] ) ) : wc_price( $prices[0] );

    // Sale Price
    $prices = array( $product->get_variation_regular_price( 'min', true ), $product->get_variation_regular_price( 'max', true ) );
    sort( $prices );
    $saleprice = $prices[0] !== $prices[1] ? sprintf( __( 'From: %1$s', 'woocommerce' ), wc_price( $prices[0] ) ) : wc_price( $prices[0] );

    if ( $price !== $saleprice ) {
        $price = '<del>' . $saleprice . '</del> <ins>' . $price . '</ins>';
    }
    
    return $price;
}
add_filter( 'woocommerce_variable_sale_price_html', 'wc_ninja_custom_variable_price', 10, 2 );
add_filter( 'woocommerce_variable_price_html', 'wc_ninja_custom_variable_price', 10, 2 );

Does this code need updating to WooCommerce 3+?

eg. $string = WC_Product_Variable::get_variation_price( $min_or_max, $for_display );

http://woocommerce.wp-a2z.org/oik_api/wc_product_variableget_variation_price/