Regarding your adwords strategy, you should talk to HN user zackattack. He's really good and recently helped me test some ideas.
Have you thought of making add-on tools for the big GIS software? For example, we used to use this one a lot - http://www.spatialecology.com/htools/tooldesc.php. You could possibly start with selling small scripts which fix problems people mention on the ESRI forums and build up a toolbox over time, which you could then sell as a package.
That way, you have a readymade market.
Earning karma by helping people on forums is probably your equivalent for an SEO strategy here.
EDIT: Oh and $10 is wayyy too low. Don't charger per conversion. If someone needs this tool, they are going to use it a lot, not just once. Charge at least $100 for unlimited conversions. Then charge more when your product is better. Even if your adwords CTR is low, at least make it count.