Exactly right, usually a high gravity is good because it means tons of people promoting so it must be making money - but if you have low gravity very little comp and if you find the right kw = $$$Gravity gives you an idea of the amount of other people promoting the product. If it has 4,400 monthly searches and little to no competition, it's a good bet to spend $10/year for a domain name as you'll make that with a crappy website in just one sale. Best of luck to you!