I know it sounds kinda harsh, but for one thing you will find no such company because they would be spammers (or, at least spammer aids) by default. The people you are trying to contact did not ask you to contact them, so you will be spamming them. It doesn't seem like it to you, because you're the one doing it and you surely mean no ill-will, but it would be spam nonetheless.
My parents run a small accounting firm and "spam" snail mail to everyone that buys a new home, they buy a list from the city I believe. I don't know, but this is probably too small scale for your clients
My point is, if you do email these people it will be spam. I'm not saying email is a bad idea, just keep that in mind. You don't have to limit yourself to electronic advertisement, either. Posting an ad in a local paper with your website is not a bad idea.