There are a huge lot of altcoins already. All being more or less "cryptocurrencies like Bitcoin". So your logic of missed opportunity is not good, since the altcoins have shown that they don't have the potential of becoming as important as Bitcoin.

Making a clone of Bitcoin or a fork of bitcoin are not that difficult, hence I don't expect it to be that expensive, but this will most probably not be a good business for you, you will not earn that money back.