Where can one purchase a local email list for email marketing?

google it and  you will find some one who saleing it

You'll want to work with a reputable data provider - such as infoUSA, ZoomInfo or DatabaseUSA. The cost per lead depends on how targeted your email list is - the more highly targeted, the more it'll cost per lead. I would suggest asking for a sample list before going through with a purchase to ensure the data is top-notch. Here's a great article on3 questions you should ask any lead generation company: http://blog.clickback.com/index.php/lead-generation-companies-the-3-key-questions-to-ask/

There are many, many companies that sell email lists and can be found in a simple search.

InfoUSA and Hoovers are among the oldest and most reliable sources. Good Email lists are not cheap. Expect to pay $1 or more per name depending on the list.