Google and Yahoo offer cost-per-click campaigns using keywords. You basically register, give your add a title and write 2 brief lines describing your website and services. I`ve used it with much success with an earlier project I did after 9/11 called the www.911patchproject.org You set your montly campaign. Start out with $100 to $200 month and see how your site traffic improves. Many companies average a $5000 month campaign looking for banners and video ad`s to get 1million impressions are various popular sites.
As for hard numbers, the more you can invest in traditional advertising (print ad`s, magazines and news) the better off you will be considering you are looking at a 1-3% return on your advertising. Beyond operations and salaries, it is your highest cost.
I did well using FREE and low cost Internet campaigns. Also register your site with www.Alexa.com this site ranks website traffic. The higher your ranking, the more you are worth. You can use "organic" strategies. In other words, link to as many sites as you can. This isn`t providing website links on a seperate page but incorporating links, bolding them and hignlighting them in blue throughout your web pages. A great example of how to do this is to go to Wikipedia and your`ll see all the links incorporated in just about every paragraph. Then run the site on Alexa and you`ll see their ranking.
Not hard numbers you were looking for but at least a way to begin strengthening you ranking and driving people to your site. Blogs are really good for this as well. Post everywhere you possiblly can. Spend money to hire a blogger as it is money well spent!
An online collaborative encyclopedia.
wikipedia.com