Is it a better idea, in terms of getting lower prices, to look at airports that are busier?
Bigger airports doesn't necessarily mean better fares. I would say that the competition on a specific route is key to better fares.
I live for example in Belgium, but often fly from Amsterdam airport. Some airlines consider main train stations as airports, so I can book a airplane ticket from the train station of my home town to almost anywhere, "transferring" at Amsterdam airport. Often I pay less then a passenger on the same flight leaving Amsterdam, who boarded in Amsterdam directly. I guess it mainly boils down to pulling passengers away from Brussels airport.
So to find the better fares try to identify which carriers offer a specific route.