what's the cheapest way to buy online traffic?

Answer 1

In order to get traffic you have to attract people to your site. You can't really "buy traffic." You can pay people to help you generate traffic, but that can be very expensive. There are Web rings that you can join, and some people post links in a lot of forums, blogs, etc. You could also try to get free links on some popular sites by contacting the web masters. The cheap ways take longer and are more work. It's like everything else in life, you get what you pay for.

Answer 2

Google adwords.