Try this code:
add_filter('woocommerce_variable_price_html', 'custom_variation_price', 10, 2);
function custom_variation_price( $price, $product ) {
$available_variations = $product->get_available_variations();
$selectedPrice="";
$dump = '';
foreach ( $available_variations as $variation )
{
// $dump = $dump . '<pre>' . var_export($variation['attributes'], true) . '</pre>';
$isDefVariation=false;
foreach($product->get_default_attributes() as $key=>$val){
// $dump = $dump . '<pre>' . var_export($key, true) . '</pre>';
// $dump = $dump . '<pre>' . var_export($val, true) . '</pre>';
if($variation['attributes']['attribute_'.$key]==$val){
$isDefVariation=true;
}
}
if($isDefVariation){
$price = $variation['display_price'];
}
}
$selectedPrice = wc_price($price);
// $dump = $dump . '<pre>' . var_export($available_variations, true) . '</pre>';
return $selectedPrice . $dump;
}