Retrieve information with PHP and CURL

I need a function (PHP / CURL) to retrieve the final value calculated at site: [login to view URL] For testing purpose put at field "Cep Origem" and "Cep Destino" the number: 13179080 At field Peso put 1 and leave others as default. Click at button "Enviar" and see the price of R$ 14,7. I need the function return me only the value 14,7