Example of non-buyer Keyword
"free red widgets
download red widgets"
Example of generic keyword
red widgets
what are red widgets
Example of buyer keywords
buy red widgets online
red widgets online store
red widget deal
red widget discount
purchase red widgets
red widgets in new york
generally speaking, the longer your target keyword is, the more likely it will convert. Conversely, you may receive less traffic to it.
For example, if you rank #1 for a two word keyword, you will likely get 20% of the search volume to your website.
However if you are #1 for a four word keyword, that figure is approximately 35%, even higher if you use Microdata, there are few ads and you have multiple results on the first page.
Other type of keywords is to identify what the product is helping a user with if they purchase it.
Target content that have words like 'stop' 'help' 'how to' 'why can't I' that will bring other potential converts.
How is the copywriting on the site? Does it play on the psychology of the seller's mindset?