So it is with online. Let's say my client, Site X, has 1 million impressions left unsold every month. Of course not. This may seem like a no-brainer postulate, but most people out there don't think this way. Barter gets treated like an after-thought.
Attention is paid to it at the front end, but no one is watching over it on the back end.
First things first. Determine the value of what it is that you want to trade. This is the most common form of barter. Rate card value for rate card value. Site publishers, though they prefer cash, of course, like this system of barter because the determined value of the exchange is realized as actual revenue on the bottom line.