Budget can be anything from 10 cents (daily impressions) to 100,000 dollars (for a specific period of time).
Classifieds would offer more economical rates such as
Online-Advertising-Rates.Blogspot.com
Prices vary considerably, often the effectiveness of the traffic the ad attracts is proportioned to the ad cost.
Higher quality ads, like sponsored search results that appear on page one of search results of people with your selected topic on their minds can cost $0.50 to $5.00 per click for most.
You can get 1000 impressions of a banner ad on junkier sites for as low as 10 cents.
With google adsense/adwords, you can spend $5 or even more for each click on your ad. With ptc sites you can expose your ad, splash page, etc to 1000s for pennies per click. If you want a list of ad networks that Vick S. put together email me.
jmheltonptc@yahoo.com
Like most things it costs as much as you are willing to spend.
