I am trying to do keyword research for a site I am building, and I have been using Google's Adwords research tool. However, every time I find a keyword with a high number of average searches, a friend of mine who is an SEO consultant plugs the same keyword into his research tool and says he's not finding any searches at all. He won't let me access the tool because it is proprietary, so is there another keyword research tool out there that is free to use? I only ask for a free one because I am building just one site, and will only be using the tool a few times.
It sounds like your friend's tool isn't very accurate. Google has more stats about keyword searches than anyone else. Of course they want to provide their advertisers with lists of good keywords that they can spend money on. It wouldn't make sense for them to claim false numbers about keyword search volume. Just trust what Google is telling you about the keywords. If Google says there is high volume and your buddy's tool is not showing anything at all then something is wrong.