I like taking public transportation, so I usually try to take the bus. The first one leaves at 6 am, from the Plaza Galicia, about a 5 minute walk from the cathedral. They leave every half hour. It does take a roundabout route, though, going first to the train station, then the bus station, and then to the airport. But the ride is not much more than a half hour I think and is just a couple of euros. (maybe three?). The taxi rate has gone up a euro or two, it's now 21 or 22.
The bus route takes you through the "center" of Lavacolla, so you will almost always see pilgrims crossing the highway near the church to begin the ascent. I always like that part of the trip, though it usually does fill me with an urge to bolt from the bus and continue walking. Buen camino, Laurie