I got a new barrel out on a Marlin 1895. The barrel came from Numrich gun parts at a reasonable price and gunsmithing fees were reasonable as well.
Having said that if it is the rifling that is pitted I'd suggest shooting a box or two of ammo through it before making any decisions. About 20 years ago I bought a used Ruger #1V. 22-250 I brought it home from the gun shop and proceeded to shoot 1/2"groups. All was fine until I cleaned it. I was shocked that it was actually quite pitted inside the barrel. Getting back to the range the best it could do was 1.5" groups until it got fouled again. Once the fouling filled in the pitting, which took about 15 rounds, it was back to 1/2" groups. Your .30-30 might shoot well as it.