I have never once regretted the cost of the custom actions I have used.
I have also had a couple of factory actions accurized, and they were really good too. I think probably the least expensive way to a really accurate rifle is to use the factory barreled action, have it all trued, including a trigger job, and bed it into a good stock. Go see the Harvester series at Hill Country Rifles for an example.
I had an old Ruger tang safety in 7 rem mag done this way. I ended up with a rifle that shot in the .4's after load development. I didn't shoot much big game with it, but I did shoot a boat load of prairie dogs.