As with any type of advertising you can get mixed results.
The best thing to do in all honesty is to write a couple of articles for the various webmaster newslettter sites and hope they get published prior to spending $$$ on an advertising campaign.
After you have perhaps 2 or 3 of the articles published you should be able to get an idea of the traffic levels you should receive from a range of advertising mediums such as text links and buttons / banners.
As a webmaster newsletter owner i can honestly say that fr the most part, companies who advertise in the newsletter itself do not do as well as those companies who advertise on the physical site of the newsletter to which we supply links to individual articles.
If you are interested in finding out more shoot an email across to
[email protected] and ask her about details for a marketing campaign in the
http://www.adultwebmasternewsletter.com 
Regards,
Lee