The GW offshoot company "Specials Games" (or Fantatic at one point) is slowly dissolving and being merged back into the main GW company. And the rule books will now be available free online to download as "Living Rulebooks".
This means that you can go to (for example) http://www.specialist-games.com/inquisitor/tlr.asp and download the Living Rulebook which contains all of the rules and latest errata in one PDF file!
They'll still be charging for models, but its a good start Now, if only I had more time and some people to play against!