If your site isn't converting, optimizing to bring in more traffic may be premature. Bringing through more traffic to a site that (for whatever reason) doesn't "resonate" with visitors is just a waste of bandwidth.
You'll get a lot more "bang for the buck" by focusing your attention first on finding and fixing whatever the problems are that are stopping people from buying.
You know the product is good, because -- as you say -- people "snatch them up" at tradeshows. Try thinking about what you do or say differently at those tradeshows compared to what you do and say on your website. It could just be a matter of rewriting some of your web copy, updating to higher quality product images or adding a trust seal or two to your checkout page.
In other words, there are probably things you can do right now, without redesigning your entire website, that could start bringing in more sales and revenue.
You might want to check out some resources like Marketing Experiments (www.marketingexperiments.com
), Psychotactics (www.psychotactics.com
) and Grokdotcom (www.grokdotcom.com
) to learn more about things you can do to maximize conversions.
As others here have said, there's no real reason why you have to choose between product-related keywords and "education" related keywords. In fact, especially if you're optimizing for organic search, you want to cast your net wide when it comes to keywords, so I'd definitely try to go for both if it were me.