Endless Visitors
http://www.endlessvisitors.com

1,000 untargeted visitors $1.75
1,000 geo+category targeted visitors $3.50

If you have questions regarding how it all works, you can visit our FAQ page.
FAQ page: http://www.endlessvisitors.com/faq.php

Your campaign consists of 24Hour unique visitors that you can set a daily cap for, as well as change the campaign URL during your campaign (all you need to do is send an e-mail with the new URL).