Website with Budget Airlines

If you are used to booking flights with sites like Orbitz (www.orbitz,com) or Travelocity (www.travelocity.com) you probably realize that they often don't include the cheapest flights, because many budget airlines do not participate in their bookings. Therefore, you miss out on flights with companies like Ryanair (www.ryanair.com) and similar European carriers which often greatly undercut the major airlines.
Now there is a Website www.whichbudget.com, that includes all the possible flights between two destinations. The downside is that they direct you to the site of the airlines, you don't seem to be able to book directly with them.
I checked for a route that would interest me, Montreal to Moscow, but unfortunately I couldn't anything under $1300 or so. These seem to be two markets where budget airlines just are not an option. Even checking London to Moscow didn't reduce the cost very much.
However, if you are travelling in countries other than Russia and Canada, this site could be very helpful. (Hmm, what else do Russia and Canada have in common besides huge territories and cold weather?)