equipment for wifi link 500m apart

I have 2 places...one has a gigabyte access point and one has a pci wifi card that should connect to the ap.The distance is about 500m...and the guy with the pci card is on a hill...he can see my house from his roof perfectly...and i guess i can sortof see his...
both the AP and the pci card have a RP-SMA female connector.
now...what would be the cheapest setup i can do to finish this...i thought that a RP-SMA to N type converor directly on the card/ap and then coax with the appropriate connectors...i want the antenna to be the directional kind (either parabole mesh or the can antenna sortof type,or something like this http://www.saunalahti.fi/elepal/antenna1.html). what kind of dbi i need for the antennas...and also what kind of coax do i need so that the signal doesnt loose itself ... as cheapest as possible please