Think about your audience; that is who you need to view your website. Some search engine may make a charge to list your site in other countries, this may sound good but is your site in that countries language, are you able to accept payment from there and can you deliver, (if so are there extra charges or laws to consider). Ask yourself why pay for traffic from abroad when you don't plan to make any sales there. Who is your target audience? Younger age group or more mature? Male or Female, Lower economic status or higher. Are you targeting a particular profession?
I have not used these but they sound OK, if you have the budget:-
Overture for USA
http://www.content.overture.com
Espotting for Europe
http://www.espotting.com