Now, that said, there are a whole bunch of websites that would like you to order vital records through there website so they can make some money providing you with what you can get at the best price directly from the states.
Another thing to know is the birth and death certificates are a relatively new invention. Each state has a date when that type of record is available. Going back to the Research Wiki, you can look up the states you are interested in and see if there is a certificate possible for your ancestors. If not, there is a long list of places to look for alternative birth and death information. The Research Wiki has the answers.